{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-68956", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-08-17T13:30:02.155Z", "datePublished": "2026-09-22T08:49:21.760Z", "dateUpdated": "2026-09-24T20:07:42.062Z"}, "containers": {"cna": {"affected": [{"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unknown", "modules": ["ssh_connection", "ssh_channel_sup"], "packageName": "otp", "packageURL": "pkg:software-id/erlang.org/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_connection.erl", "lib/ssh/src/ssh_channel_sup.erl"], "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}], "vendor": "Erlang", "versions": [{"changes": [{"at": "27.3.4.18", "status": "unaffected"}, {"at": "28.5.0.7", "status": "unaffected"}, {"at": "29.1.1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "18.1.2", "versionType": "otp"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unknown", "modules": ["ssh_connection", "ssh_channel_sup"], "packageName": "ssh", "packageURL": "pkg:otp/ssh", "product": "OTP", "programFiles": ["src/ssh_connection.erl", "src/ssh_channel_sup.erl"], "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "5.2.11.13", "status": "unaffected"}, {"at": "5.5.2.6", "status": "unaffected"}, {"at": "6.0.6", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "4.1.1", "versionType": "otp"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unknown", "modules": ["ssh_connection", "ssh_channel_sup"], "packageName": "erlang/otp", "packageURL": "pkg:github/erlang/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_connection.erl", "lib/ssh/src/ssh_channel_sup.erl"], "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "79c2d2be17d902c5f53969b5806b725efda831be", "status": "unaffected"}, {"at": "e18100975f0e5a8d59d02de00df12247a91b443b", "status": "unaffected"}, {"at": "e2bbad0107bba41491a4d549686fd023db8740da", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "84df3d4d0278e21a36a453bfee94799f0df67c2a", "versionType": "git"}, {"lessThan": "*", "status": "unaffected", "version": "79c2d2be17d902c5f53969b5806b725efda831be", "versionType": "git"}, {"lessThan": "*", "status": "unaffected", "version": "e18100975f0e5a8d59d02de00df12247a91b443b", "versionType": "git"}, {"lessThan": "*", "status": "unaffected", "version": "e2bbad0107bba41491a4d549686fd023db8740da", "versionType": "git"}]}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "27.3.4.18", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "28.5.0.7", "versionStartIncluding": "28.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "29.1.1", "versionStartIncluding": "29.0", "vulnerable": true}], "negate": false, "operator": "OR"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "remediation developer", "value": "Micha\u0142 W\u0105sowski / Ericsson"}, {"lang": "en", "type": "remediation reviewer", "value": "Jakub Witczak / Ericsson"}], "datePublic": "2026-09-22T08:49:22.000Z", "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler.</p>\n<p>The <code>\"session\"</code> clause of <code>ssh_connection:handle_msg/4</code> checks only <code>minimal_remote_max_packet_size</code> before calling <code>setup_session/5</code>, which unconditionally builds a <code>#channel{}</code> record and stores it in the ETS channel cache. The <code>max_channels</code> daemon option is consulted only by <code>ssh_channel_sup:max_num_channels_not_exceeded/2</code>, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable.</p>\n<p>This issue affects OTP from OTP&nbsp;18.1.2 before OTP&nbsp;27.3.4.18, OTP&nbsp;28.5.0.7, and OTP&nbsp;29.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP&nbsp;18.1.2, corresponding to ssh before 4.1.1, is affected is unknown.</p>"}, {"base64": false, "type": "text/markdown", "value": "Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler.\n\nThe `\"session\"` clause of `ssh_connection:handle_msg/4` checks only `minimal_remote_max_packet_size` before calling `setup_session/5`, which unconditionally builds a `#channel{}` record and stores it in the ETS channel cache. The `max_channels` daemon option is consulted only by `ssh_channel_sup:max_num_channels_not_exceeded/2`, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable.\n\nThis issue affects OTP from OTP\u00a018.1.2 before OTP\u00a027.3.4.18, OTP\u00a028.5.0.7, and OTP\u00a029.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP\u00a018.1.2, corresponding to ssh before 4.1.1, is affected is unknown."}], "value": "Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler.\n\nThe \"session\" clause of ssh_connection:handle_msg/4 checks only minimal_remote_max_packet_size before calling setup_session/5, which unconditionally builds a #channel{} record and stores it in the ETS channel cache. The max_channels daemon option is consulted only by ssh_channel_sup:max_num_channels_not_exceeded/2, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable.\n\nThis issue affects OTP from OTP\u00a018.1.2 before OTP\u00a027.3.4.18, OTP\u00a028.5.0.7, and OTP\u00a029.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP\u00a018.1.2, corresponding to ssh before 4.1.1, is affected is unknown."}], "impacts": [{"capecId": "CAPEC-125", "descriptions": [{"lang": "en", "value": "CAPEC-125 Flooding"}]}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "baseScore": 7.1, "baseSeverity": "HIGH", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-770", "description": "CWE-770 Allocation of Resources Without Limits or Throttling", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-09-24T20:07:42.062Z"}, "references": [{"name": "GitHub Advisory", "tags": ["related", "vendor-advisory"], "url": "https://github.com/erlang/otp/security/advisories/GHSA-qhcm-px9c-rvfh"}, {"name": "EEF CNA record for CVE-2026-68956", "tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-68956.html"}, {"name": "OSV record EEF-CVE-2026-68956", "tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-68956"}, {"name": "Erlang/OTP version ordering", "tags": ["x_version-scheme"], "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions"}, {"name": "Introducing commit 84df3d4 in erlang/otp", "tags": ["related"], "url": "https://github.com/erlang/otp/commit/84df3d4d0278e21a36a453bfee94799f0df67c2a"}, {"name": "Fix commit 79c2d2b in erlang/otp", "tags": ["patch"], "url": "https://github.com/erlang/otp/commit/79c2d2be17d902c5f53969b5806b725efda831be"}, {"name": "Fix commit e181009 in erlang/otp", "tags": ["patch"], "url": "https://github.com/erlang/otp/commit/e18100975f0e5a8d59d02de00df12247a91b443b"}, {"name": "Fix commit e2bbad0 in erlang/otp", "tags": ["patch"], "url": "https://github.com/erlang/otp/commit/e2bbad0107bba41491a4d549686fd023db8740da"}], "source": {"discovery": "INTERNAL"}, "title": "SSH daemon allocates unbounded idle session channels, bypassing max_channels", "workarounds": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>No option bounds the number of idle session channels, so the following reduce exposure without eliminating the issue.</p>\n<ul>\n<li>Restrict network access to the SSH daemon to trusted clients. Exploitation requires a successfully authenticated session, so limiting who can authenticate is the most effective control available.</li>\n<li>Set the <code>max_sessions</code> daemon option to a finite value to bound the number of concurrent connections. This limits how many connections can mount the attack in parallel, though a single connection still suffices to exhaust memory.</li>\n<li>Apply operating-system or firewall connection-rate and connection-count limits per source address.</li>\n<li>Monitor node memory externally and restart the emulator when it exceeds a threshold.</li>\n</ul>\n<p>Setting <code>max_channels</code> is not a workaround: idle session channels bypass that check entirely.</p>"}, {"base64": false, "type": "text/markdown", "value": "No option bounds the number of idle session channels, so the following reduce exposure without eliminating the issue.\n\n* Restrict network access to the SSH daemon to trusted clients. Exploitation requires a successfully authenticated session, so limiting who can authenticate is the most effective control available.\n* Set the `max_sessions` daemon option to a finite value to bound the number of concurrent connections. This limits how many connections can mount the attack in parallel, though a single connection still suffices to exhaust memory.\n* Apply operating-system or firewall connection-rate and connection-count limits per source address.\n* Monitor node memory externally and restart the emulator when it exceeds a threshold.\n\nSetting `max_channels` is not a workaround: idle session channels bypass that check entirely."}], "value": "No option bounds the number of idle session channels, so the following reduce exposure without eliminating the issue.\n\n* Restrict network access to the SSH daemon to trusted clients. Exploitation requires a successfully authenticated session, so limiting who can authenticate is the most effective control available.\n* Set the max_sessions daemon option to a finite value to bound the number of concurrent connections. This limits how many connections can mount the attack in parallel, though a single connection still suffices to exhaust memory.\n* Apply operating-system or firewall connection-rate and connection-count limits per source address.\n* Monitor node memory externally and restart the emulator when it exceeds a threshold.\n\nSetting max_channels is not a workaround: idle session channels bypass that check entirely."}]}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-68956", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-22T10:12:21.867151Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-22T10:25:30.750Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-68956", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-22T10:12:21.867151Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-22T10:15:32.927Z"}}], "cna": {"title": "SSH daemon allocates unbounded idle session channels, bypassing max_channels", "source": {"discovery": "INTERNAL"}, "credits": [{"lang": "en", "type": "remediation developer", "value": "Micha\u0142 W\u0105sowski / Ericsson"}, {"lang": "en", "type": "remediation reviewer", "value": "Jakub Witczak / Ericsson"}], "impacts": [{"capecId": "CAPEC-125", "descriptions": [{"lang": "en", "value": "CAPEC-125 Flooding"}]}], "metrics": [{"format": "CVSS", "cvssV4_0": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 7.1, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "vendor": "Erlang", "modules": ["ssh_connection", "ssh_channel_sup"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "27.3.4.18", "status": "unaffected"}, {"at": "28.5.0.7", "status": "unaffected"}, {"at": "29.1.1", "status": "unaffected"}], "version": "18.1.2", "lessThan": "*", "versionType": "otp"}], "packageURL": "pkg:software-id/erlang.org/otp", "packageName": "otp", "programFiles": ["lib/ssh/src/ssh_connection.erl", "lib/ssh/src/ssh_channel_sup.erl"], "defaultStatus": "unknown", "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "modules": ["ssh_connection", "ssh_channel_sup"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "5.2.11.13", "status": "unaffected"}, {"at": "5.5.2.6", "status": "unaffected"}, {"at": "6.0.6", "status": "unaffected"}], "version": "4.1.1", "lessThan": "*", "versionType": "otp"}], "packageURL": "pkg:otp/ssh", "packageName": "ssh", "programFiles": ["src/ssh_connection.erl", "src/ssh_channel_sup.erl"], "defaultStatus": "unknown", "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "modules": ["ssh_connection", "ssh_channel_sup"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "79c2d2be17d902c5f53969b5806b725efda831be", "status": "unaffected"}, {"at": "e18100975f0e5a8d59d02de00df12247a91b443b", "status": "unaffected"}, {"at": "e2bbad0107bba41491a4d549686fd023db8740da", "status": "unaffected"}], "version": "84df3d4d0278e21a36a453bfee94799f0df67c2a", "lessThan": "*", "versionType": "git"}, {"status": "unaffected", "version": "79c2d2be17d902c5f53969b5806b725efda831be", "lessThan": "*", "versionType": "git"}, {"status": "unaffected", "version": "e18100975f0e5a8d59d02de00df12247a91b443b", "lessThan": "*", "versionType": "git"}, {"status": "unaffected", "version": "e2bbad0107bba41491a4d549686fd023db8740da", "lessThan": "*", "versionType": "git"}], "packageURL": "pkg:github/erlang/otp", "packageName": "erlang/otp", "programFiles": ["lib/ssh/src/ssh_connection.erl", "lib/ssh/src/ssh_channel_sup.erl"], "collectionURL": "https://github.com", "defaultStatus": "unknown", "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}]}], "datePublic": "2026-09-22T08:49:22.000Z", "references": [{"url": "https://github.com/erlang/otp/security/advisories/GHSA-qhcm-px9c-rvfh", "name": "GitHub Advisory", "tags": ["related", "vendor-advisory"]}, {"url": "https://cna.erlef.org/cves/CVE-2026-68956.html", "name": "EEF CNA record for CVE-2026-68956", "tags": ["related"]}, {"url": "https://osv.dev/vulnerability/EEF-CVE-2026-68956", "name": "OSV record EEF-CVE-2026-68956", "tags": ["related"]}, {"url": "https://www.erlang.org/doc/system/versions.html#order-of-versions", "name": "Erlang/OTP version ordering", "tags": ["x_version-scheme"]}, {"url": "https://github.com/erlang/otp/commit/84df3d4d0278e21a36a453bfee94799f0df67c2a", "name": "Introducing commit 84df3d4 in erlang/otp", "tags": ["related"]}, {"url": "https://github.com/erlang/otp/commit/79c2d2be17d902c5f53969b5806b725efda831be", "name": "Fix commit 79c2d2b in erlang/otp", "tags": ["patch"]}, {"url": "https://github.com/erlang/otp/commit/e18100975f0e5a8d59d02de00df12247a91b443b", "name": "Fix commit e181009 in erlang/otp", "tags": ["patch"]}, {"url": "https://github.com/erlang/otp/commit/e2bbad0107bba41491a4d549686fd023db8740da", "name": "Fix commit e2bbad0 in erlang/otp", "tags": ["patch"]}], "workarounds": [{"lang": "en", "value": "No option bounds the number of idle session channels, so the following reduce exposure without eliminating the issue.\n\n* Restrict network access to the SSH daemon to trusted clients. Exploitation requires a successfully authenticated session, so limiting who can authenticate is the most effective control available.\n* Set the max_sessions daemon option to a finite value to bound the number of concurrent connections. This limits how many connections can mount the attack in parallel, though a single connection still suffices to exhaust memory.\n* Apply operating-system or firewall connection-rate and connection-count limits per source address.\n* Monitor node memory externally and restart the emulator when it exceeds a threshold.\n\nSetting max_channels is not a workaround: idle session channels bypass that check entirely.", "supportingMedia": [{"type": "text/html", "value": "<p>No option bounds the number of idle session channels, so the following reduce exposure without eliminating the issue.</p>\n<ul>\n<li>Restrict network access to the SSH daemon to trusted clients. Exploitation requires a successfully authenticated session, so limiting who can authenticate is the most effective control available.</li>\n<li>Set the <code>max_sessions</code> daemon option to a finite value to bound the number of concurrent connections. This limits how many connections can mount the attack in parallel, though a single connection still suffices to exhaust memory.</li>\n<li>Apply operating-system or firewall connection-rate and connection-count limits per source address.</li>\n<li>Monitor node memory externally and restart the emulator when it exceeds a threshold.</li>\n</ul>\n<p>Setting <code>max_channels</code> is not a workaround: idle session channels bypass that check entirely.</p>", "base64": false}, {"type": "text/markdown", "value": "No option bounds the number of idle session channels, so the following reduce exposure without eliminating the issue.\n\n* Restrict network access to the SSH daemon to trusted clients. Exploitation requires a successfully authenticated session, so limiting who can authenticate is the most effective control available.\n* Set the `max_sessions` daemon option to a finite value to bound the number of concurrent connections. This limits how many connections can mount the attack in parallel, though a single connection still suffices to exhaust memory.\n* Apply operating-system or firewall connection-rate and connection-count limits per source address.\n* Monitor node memory externally and restart the emulator when it exceeds a threshold.\n\nSetting `max_channels` is not a workaround: idle session channels bypass that check entirely.", "base64": false}]}], "descriptions": [{"lang": "en", "value": "Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler.\n\nThe \"session\" clause of ssh_connection:handle_msg/4 checks only minimal_remote_max_packet_size before calling setup_session/5, which unconditionally builds a #channel{} record and stores it in the ETS channel cache. The max_channels daemon option is consulted only by ssh_channel_sup:max_num_channels_not_exceeded/2, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable.\n\nThis issue affects OTP from OTP\u00a018.1.2 before OTP\u00a027.3.4.18, OTP\u00a028.5.0.7, and OTP\u00a029.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP\u00a018.1.2, corresponding to ssh before 4.1.1, is affected is unknown.", "supportingMedia": [{"type": "text/html", "value": "<p>Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler.</p>\n<p>The <code>\"session\"</code> clause of <code>ssh_connection:handle_msg/4</code> checks only <code>minimal_remote_max_packet_size</code> before calling <code>setup_session/5</code>, which unconditionally builds a <code>#channel{}</code> record and stores it in the ETS channel cache. The <code>max_channels</code> daemon option is consulted only by <code>ssh_channel_sup:max_num_channels_not_exceeded/2</code>, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable.</p>\n<p>This issue affects OTP from OTP&nbsp;18.1.2 before OTP&nbsp;27.3.4.18, OTP&nbsp;28.5.0.7, and OTP&nbsp;29.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP&nbsp;18.1.2, corresponding to ssh before 4.1.1, is affected is unknown.</p>", "base64": false}, {"type": "text/markdown", "value": "Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler.\n\nThe `\"session\"` clause of `ssh_connection:handle_msg/4` checks only `minimal_remote_max_packet_size` before calling `setup_session/5`, which unconditionally builds a `#channel{}` record and stores it in the ETS channel cache. The `max_channels` daemon option is consulted only by `ssh_channel_sup:max_num_channels_not_exceeded/2`, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable.\n\nThis issue affects OTP from OTP\u00a018.1.2 before OTP\u00a027.3.4.18, OTP\u00a028.5.0.7, and OTP\u00a029.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP\u00a018.1.2, corresponding to ssh before 4.1.1, is affected is unknown.", "base64": false}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-770", "description": "CWE-770 Allocation of Resources Without Limits or Throttling"}]}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "27.3.4.18"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "28.5.0.7", "versionStartIncluding": "28.0"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "29.1.1", "versionStartIncluding": "29.0"}], "operator": "OR"}], "operator": "AND"}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-09-24T20:07:42.062Z"}}}, "cveMetadata": {"cveId": "CVE-2026-68956", "state": "PUBLISHED", "dateUpdated": "2026-09-24T20:07:42.062Z", "dateReserved": "2026-08-17T13:30:02.155Z", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "datePublished": "2026-09-22T08:49:21.760Z", "assignerShortName": "EEF"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unknown", "modules": ["ssh_connection", "ssh_channel_sup"], "packageName": "otp", "packageURL": "pkg:software-id/erlang.org/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_connection.erl", "lib/ssh/src/ssh_channel_sup.erl"], "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}], "vendor": "Erlang", "versions": [{"changes": [{"at": "27.3.4.18", "status": "unaffected"}, {"at": "28.5.0.7", "status": "unaffected"}, {"at": "29.1.1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "18.1.2", "versionType": "otp"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unknown", "modules": ["ssh_connection", "ssh_channel_sup"], "packageName": "ssh", "packageURL": "pkg:otp/ssh", "product": "OTP", "programFiles": ["src/ssh_connection.erl", "src/ssh_channel_sup.erl"], "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "5.2.11.13", "status": "unaffected"}, {"at": "5.5.2.6", "status": "unaffected"}, {"at": "6.0.6", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "4.1.1", "versionType": "otp"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unknown", "modules": ["ssh_connection", "ssh_channel_sup"], "packageName": "erlang/otp", "packageURL": "pkg:github/erlang/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_connection.erl", "lib/ssh/src/ssh_channel_sup.erl"], "programRoutines": [{"name": "ssh_connection:handle_msg/4"}, {"name": "ssh_connection:setup_session/5"}, {"name": "ssh_channel_sup:max_num_channels_not_exceeded/2"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "79c2d2be17d902c5f53969b5806b725efda831be", "status": "unaffected"}, {"at": "e18100975f0e5a8d59d02de00df12247a91b443b", "status": "unaffected"}, {"at": "e2bbad0107bba41491a4d549686fd023db8740da", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "84df3d4d0278e21a36a453bfee94799f0df67c2a", "versionType": "git"}, {"lessThan": "*", "status": "unaffected", "version": "79c2d2be17d902c5f53969b5806b725efda831be", "versionType": "git"}, {"lessThan": "*", "status": "unaffected", "version": "e18100975f0e5a8d59d02de00df12247a91b443b", "versionType": "git"}, {"lessThan": "*", "status": "unaffected", "version": "e2bbad0107bba41491a4d549686fd023db8740da", "versionType": "git"}]}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler.\n\nThe \"session\" clause of ssh_connection:handle_msg/4 checks only minimal_remote_max_packet_size before calling setup_session/5, which unconditionally builds a #channel{} record and stores it in the ETS channel cache. The max_channels daemon option is consulted only by ssh_channel_sup:max_num_channels_not_exceeded/2, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable.\n\nThis issue affects OTP from OTP\u00a018.1.2 before OTP\u00a027.3.4.18, OTP\u00a028.5.0.7, and OTP\u00a029.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP\u00a018.1.2, corresponding to ssh before 4.1.1, is affected is unknown."}], "id": "CVE-2026-68956", "lastModified": "2026-09-24T21:17:30.590", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-68956", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-09-22T10:12:21.867151Z", "version": "2.0.3"}}]}, "published": "2026-09-22T09:17:05.313", "references": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://cna.erlef.org/cves/CVE-2026-68956.html"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/erlang/otp/commit/79c2d2be17d902c5f53969b5806b725efda831be"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/erlang/otp/commit/84df3d4d0278e21a36a453bfee94799f0df67c2a"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/erlang/otp/commit/e18100975f0e5a8d59d02de00df12247a91b443b"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/erlang/otp/commit/e2bbad0107bba41491a4d549686fd023db8740da"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/erlang/otp/security/advisories/GHSA-qhcm-px9c-rvfh"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://osv.dev/vulnerability/EEF-CVE-2026-68956"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions"}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}]}

{}