{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-42786", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-04-29T18:06:33.251Z", "datePublished": "2026-05-01T20:34:17.014Z", "dateUpdated": "2026-05-01T20:34:17.014Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.Bandit.WebSocket.Connection'"], "packageName": "bandit", "packageURL": "pkg:hex/bandit", "product": "bandit", "programFiles": ["lib/bandit/websocket/connection.ex"], "programRoutines": [{"name": "'Elixir.Bandit.WebSocket.Connection':handle_frame/3"}], "repo": "https://github.com/mtrudel/bandit", "vendor": "mtrudel", "versions": [{"lessThan": "1.11.0", "status": "affected", "version": "0.5.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.Bandit.WebSocket.Connection'"], "packageName": "mtrudel/bandit", "packageURL": "pkg:github/mtrudel/bandit", "product": "bandit", "programFiles": ["lib/bandit/websocket/connection.ex"], "programRoutines": [{"name": "'Elixir.Bandit.WebSocket.Connection':handle_frame/3"}], "repo": "https://github.com/mtrudel/bandit", "vendor": "mtrudel", "versions": [{"lessThan": "1.11.0", "status": "affected", "version": "8909391f486d42138c5308410bc5ea49a65f4d46", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>The application must accept WebSocket connections. Applications that expose no WebSocket endpoints are not affected.</p>"}], "value": "The application must accept WebSocket connections. Applications that expose no WebSocket endpoints are not affected."}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.11.0", "versionStartIncluding": "0.5.0", "vulnerable": true}], "negate": false, "operator": "OR"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "finder", "value": "Peter Ullrich"}, {"lang": "en", "type": "remediation developer", "value": "Mat Trudel"}, {"lang": "en", "type": "analyst", "value": "Jonatan M\u00e4nnchen"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.<p>The fragment reassembly path in <tt>'Elixir.Bandit.WebSocket.Connection':handle_frame/3</tt> in <tt>lib/bandit/websocket/connection.ex</tt> appends every incoming <tt>Continuation{fin: false}</tt> frame's payload to a per-connection iolist with no cumulative size cap. The existing <tt>max_frame_size</tt> option only bounds individual frames; a peer that streams an unbounded number of continuation frames without ever setting <tt>fin=1</tt> grows BEAM heap linearly until the OS or a supervisor kills the process.</p><p>Because the accumulation happens before <tt>WebSock.handle_in/2</tt> is called, the application has no opportunity to interpose a size check. Phoenix Channels and LiveView both run over <tt>WebSock</tt> on Bandit, so a stock Phoenix application exposes this surface as soon as it accepts socket connections.</p><p>This issue affects bandit: from 0.5.0 before 1.11.0.</p>"}], "value": "Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.\n\nThe fragment reassembly path in 'Elixir.Bandit.WebSocket.Connection':handle_frame/3 in lib/bandit/websocket/connection.ex appends every incoming Continuation{fin: false} frame's payload to a per-connection iolist with no cumulative size cap. The existing max_frame_size option only bounds individual frames; a peer that streams an unbounded number of continuation frames without ever setting fin=1 grows BEAM heap linearly until the OS or a supervisor kills the process.\n\nBecause the accumulation happens before WebSock.handle_in/2 is called, the application has no opportunity to interpose a size check. Phoenix Channels and LiveView both run over WebSock on Bandit, so a stock Phoenix application exposes this surface as soon as it accepts socket connections.\n\nThis issue affects bandit: from 0.5.0 before 1.11.0."}], "impacts": [{"capecId": "CAPEC-130", "descriptions": [{"lang": "en", "value": "CAPEC-130 Excessive Allocation"}]}], "metrics": [{"cvssV4_0": {"attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "baseScore": 8.7, "baseSeverity": "HIGH", "privilegesRequired": "NONE", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE"}, "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": "2026-05-01T20:34:17.014Z"}, "references": [{"tags": ["vendor-advisory", "related"], "url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-pf94-94m9-536p"}, {"tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-42786.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-42786"}, {"tags": ["patch"], "url": "https://github.com/mtrudel/bandit/commit/21612c7c7b1ce43eccd36d3af3a2299d23513667"}], "source": {"discovery": "EXTERNAL"}, "title": "WebSocket fragmented message reassembly unbounded in bandit", "x_generator": {"engine": "cvelib 1.8.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.\n\nThe fragment reassembly path in 'Elixir.Bandit.WebSocket.Connection':handle_frame/3 in lib/bandit/websocket/connection.ex appends every incoming Continuation{fin: false} frame's payload to a per-connection iolist with no cumulative size cap. The existing max_frame_size option only bounds individual frames; a peer that streams an unbounded number of continuation frames without ever setting fin=1 grows BEAM heap linearly until the OS or a supervisor kills the process.\n\nBecause the accumulation happens before WebSock.handle_in/2 is called, the application has no opportunity to interpose a size check. Phoenix Channels and LiveView both run over WebSock on Bandit, so a stock Phoenix application exposes this surface as soon as it accepts socket connections.\n\nThis issue affects bandit: from 0.5.0 before 1.11.0."}], "id": "CVE-2026-42786", "lastModified": "2026-05-01T21:16:17.347", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.7, "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": "NONE", "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:N/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"}]}, "published": "2026-05-01T21:16:17.347", "references": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://cna.erlef.org/cves/CVE-2026-42786.html"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/mtrudel/bandit/commit/21612c7c7b1ce43eccd36d3af3a2299d23513667"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-pf94-94m9-536p"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://osv.dev/vulnerability/EEF-CVE-2026-42786"}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}]}

{}