{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-19445", "assignerOrgId": "28c92f92-d60d-412d-b760-e73465c3df22", "state": "PUBLISHED", "assignerShortName": "PSF", "dateReserved": "2026-08-10T13:31:21.724Z", "datePublished": "2026-09-30T16:16:04.923Z", "dateUpdated": "2026-10-03T00:36:46.398Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "modules": ["ssl"], "product": "CPython", "repo": "https://github.com/python/cpython", "vendor": "Python Software Foundation", "versions": [{"version": "0", "lessThan": "3.10.22", "status": "affected", "versionType": "python"}, {"version": "3.11.0", "lessThan": "3.11.17", "status": "affected", "versionType": "python"}, {"version": "3.12.0", "lessThan": "3.12.15", "status": "affected", "versionType": "python"}, {"version": "3.13.0", "lessThan": "3.13.16", "status": "affected", "versionType": "python"}, {"version": "3.14.0", "lessThan": "3.14.8", "status": "affected", "versionType": "python"}, {"version": "3.15.0a1", "lessThan": "3.15.0rc3", "status": "affected", "versionType": "python"}]}], "credits": [{"lang": "en", "type": "reporter", "value": "Gregory P. Smith (https://github.com/gpshead)"}, {"lang": "en", "type": "coordinator", "value": "Seth Larson (https://github.com/sethmlarson)"}, {"lang": "en", "type": "remediation reviewer", "value": "B\u00e9n\u00e9dikt Tran (https://github.com/picnixz)"}], "descriptions": [{"lang": "en", "supportingMedia": [{"type": "text/html", "value": "<p>A remote, unauthenticated TLS client can make a server crash or call\nthrough a freed pointer if its sni_callback assigns a different context to\nSSLSocket.context (the documented way to select a certificate per server\nname) and nothing else keeps the original ssl.SSLContext alive. Typical\ncases are servers that create an SSLContext per connection or replace it\nwhile connections are open; servers that wrap their listening socket with\nit are not affected.</p>\n<p>Mitigation: keep a reference to every SSLContext that sets sni_callback for\nthe lifetime of the server. TLS clients are not affected.</p>"}], "value": "A remote, unauthenticated TLS client can make a server crash or call\nthrough a freed pointer if its sni_callback assigns a different context to\nSSLSocket.context (the documented way to select a certificate per server\nname) and nothing else keeps the original ssl.SSLContext alive. Typical\ncases are servers that create an SSLContext per connection or replace it\nwhile connections are open; servers that wrap their listening socket with\nit are not affected.\n\n\nMitigation: keep a reference to every SSLContext that sets sni_callback for\nthe lifetime of the server. TLS clients are not affected."}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 9.2, "baseSeverity": "CRITICAL", "exploitMaturity": "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:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "LOW", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-416", "description": "CWE-416", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "28c92f92-d60d-412d-b760-e73465c3df22", "shortName": "PSF", "dateUpdated": "2026-10-03T00:36:46.398Z"}, "references": [{"tags": ["patch"], "url": "https://github.com/python/cpython/pull/158504"}, {"tags": ["vendor-advisory"], "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/QMQIUQB6WGGC3MI7I3WKQXOYOBDSPPS3/"}, {"tags": ["issue-tracking"], "url": "https://github.com/python/cpython/issues/156293"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/34a53dce8174da2fceb12fe084a4def02a10053d"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/46133cd57d309652139ada74014aca7665ac552b"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/63fab143d94cafae71850831acfb52041ba44af7"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/cd7e51e7d4563866fbaa1e2521ae69b45daf3698"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/d8717ed01717a9641686e6e6f83f0ab8af235e2c"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/b12968cefe69ca1dcb8606c832ff73ee7dbf4ba8"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/ec44b5a3258cbda947d5e07242ee562ed05ef24b"}], "source": {"discovery": "UNKNOWN"}, "title": "Use-after-free of a server-side SSLContext when sni_callback switches contexts", "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"title": "CVE Program Container", "references": [{"url": "http://www.openwall.com/lists/oss-security/2026/09/30/17"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2026-09-30T18:09:39.735Z"}}]}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "modules": ["ssl"], "product": "CPython", "repo": "https://github.com/python/cpython", "vendor": "Python Software Foundation", "versions": [{"lessThan": "3.10.22", "status": "affected", "version": "0", "versionType": "python"}, {"lessThan": "3.11.17", "status": "affected", "version": "3.11.0", "versionType": "python"}, {"lessThan": "3.12.15", "status": "affected", "version": "3.12.0", "versionType": "python"}, {"lessThan": "3.13.16", "status": "affected", "version": "3.13.0", "versionType": "python"}, {"lessThan": "3.14.8", "status": "affected", "version": "3.14.0", "versionType": "python"}, {"lessThan": "3.15.0rc3", "status": "affected", "version": "3.15.0a1", "versionType": "python"}]}], "source": "cna@python.org"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "A remote, unauthenticated TLS client can make a server crash or call\nthrough a freed pointer if its sni_callback assigns a different context to\nSSLSocket.context (the documented way to select a certificate per server\nname) and nothing else keeps the original ssl.SSLContext alive. Typical\ncases are servers that create an SSLContext per connection or replace it\nwhile connections are open; servers that wrap their listening socket with\nit are not affected.\n\n\nMitigation: keep a reference to every SSLContext that sets sni_callback for\nthe lifetime of the server. TLS clients are not affected."}], "id": "CVE-2026-19445", "lastModified": "2026-10-03T01:17:24.930", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 9.2, "baseSeverity": "CRITICAL", "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:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/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": "LOW", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "cna@python.org", "type": "Secondary"}]}, "published": "2026-09-30T17:16:45.720", "references": [{"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/34a53dce8174da2fceb12fe084a4def02a10053d"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/46133cd57d309652139ada74014aca7665ac552b"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/63fab143d94cafae71850831acfb52041ba44af7"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/b12968cefe69ca1dcb8606c832ff73ee7dbf4ba8"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/cd7e51e7d4563866fbaa1e2521ae69b45daf3698"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/d8717ed01717a9641686e6e6f83f0ab8af235e2c"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/ec44b5a3258cbda947d5e07242ee562ed05ef24b"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/issues/156293"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/pull/158504"}, {"source": "cna@python.org", "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/QMQIUQB6WGGC3MI7I3WKQXOYOBDSPPS3/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "http://www.openwall.com/lists/oss-security/2026/09/30/17"}], "sourceIdentifier": "cna@python.org", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-416"}], "source": "cna@python.org", "type": "Secondary"}]}

{"affected_release": [{"advisory": "RHSA-2026:74867", "cpe": "cpe:/a:redhat:hummingbird:1", "impact": "important", "package": "python3-15-main-3.15.0~rc2-1.1.hum1", "product_name": "Red Hat Hardened Images", "release_date": "2026-10-02T00:00:00Z"}], "bugzilla": {"description": "python: Use-after-free of a server-side SSLContext when sni_callback switches contexts", "id": "2544138", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2544138"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.1", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "status": "verified"}, "cwe": "CWE-416", "details": ["A remote, unauthenticated TLS client can make a server crash or call\nthrough a freed pointer if its sni_callback assigns a different context to\nSSLSocket.context (the documented way to select a certificate per server\nname) and nothing else keeps the original ssl.SSLContext alive. Typical\ncases are servers that create an SSLContext per connection or replace it\nwhile connections are open; servers that wrap their listening socket with\nit are not affected.\nMitigation: keep a reference to every SSLContext that sets sni_callback for\nthe lifetime of the server. TLS clients are not affected.", "A flaw was found in Python. A remote, unauthenticated TLS client can cause a use-after-free in a server that uses SSLContext.sni_callback to assign a different SSLSocket.context when selecting a certificate per server name, if nothing else keeps the original SSLContext alive. This can crash the server process or result in a call through a freed pointer. Servers that wrap their listening socket with a long-lived SSLContext are not affected. TLS clients are not affected."], "mitigation": {"lang": "en:us", "value": "Restrict Python TLS servers that use SSLContext.sni_callback to trusted clients. Keep a strong reference to every SSLContext that registers an SNI callback for the lifetime of the server so the original context cannot be garbage-collected while connections remain open. Prefer wrapping the listening socket with a long-lived SSLContext; that common pattern is not affected. Host heap allocator hardening increases the difficulty of turning the use-after-free into reliable code execution but does not prevent process crashes."}, "name": "CVE-2026-19445", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "impact": "important", "package_name": "python3.12", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "impact": "important", "package_name": "python3.14", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "python", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "python", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "impact": "important", "package_name": "python3", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "impact": "important", "package_name": "python3", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "impact": "important", "package_name": "python3.11", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "impact": "important", "package_name": "python3.12", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "impact": "important", "package_name": "python36:3.6/python36", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "impact": "important", "package_name": "python3.11", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "impact": "important", "package_name": "python3.12", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "impact": "important", "package_name": "python3.14", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "impact": "important", "package_name": "python3.9", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "hi/python", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "python3.10", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "python3.11", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "python3.12", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "python3.13", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "python3.14", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-09-30T16:16:04Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-19445\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-19445\nhttps://github.com/python/cpython/issues/156293\nhttps://github.com/python/cpython/pull/158504\nhttps://mail.python.org/archives/list/security-announce@python.org/thread/QMQIUQB6WGGC3MI7I3WKQXOYOBDSPPS3/"], "statement": "This issue is rated Important. A remote unauthenticated client can trigger a server-side use-after-free when SNI callback code switches SSLSocket.context and drops the last reference to the original SSLContext, which can crash the process or call through a freed pointer (C:H/I:H/A:H). It is not Critical: exploitation requires a specific, non-default server pattern (per-connection or replaced SSLContext with sni_callback); the common pattern of wrapping the listening socket is explicitly not affected, so Attack Complexity is High. Red Hat ASLR, NX, and glibc heap hardening raise the bar for reliable code execution from the UAF but do not remove the crash/DoS impact, so Availability remains High.", "threat_severity": "Important"}