{"id":"CVE-2026-19445","title":"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 el…","summary":"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 el…","severity":"critical","cvss":9.2,"cvssVector":"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","cwe":["CWE-416"],"vendor":"Python Software Foundation","product":"CPython","affected":["CPython < 3.10.22","CPython >= 3.11.0 < 3.11.17","CPython >= 3.12.0 < 3.12.15","CPython >= 3.13.0 < 3.13.16","CPython >= 3.14.0 < 3.14.8","CPython >= 3.15.0a1 < 3.15.0rc3"],"published":"2026-09-30","updated":"2026-10-03","sourceUpdated":"2026-10-03T01:17:24.930","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-19445","references":[{"url":"https://github.com/python/cpython/commit/34a53dce8174da2fceb12fe084a4def02a10053d","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/46133cd57d309652139ada74014aca7665ac552b","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/63fab143d94cafae71850831acfb52041ba44af7","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/b12968cefe69ca1dcb8606c832ff73ee7dbf4ba8","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/cd7e51e7d4563866fbaa1e2521ae69b45daf3698","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/d8717ed01717a9641686e6e6f83f0ab8af235e2c","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/ec44b5a3258cbda947d5e07242ee562ed05ef24b","label":"cna@python.org"},{"url":"https://github.com/python/cpython/issues/156293","label":"cna@python.org"},{"url":"https://github.com/python/cpython/pull/158504","label":"cna@python.org"},{"url":"https://mail.python.org/archives/list/security-announce@python.org/thread/QMQIUQB6WGGC3MI7I3WKQXOYOBDSPPS3/","label":"cna@python.org"},{"url":"http://www.openwall.com/lists/oss-security/2026/09/30/17","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-19445.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-19445"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2544138"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-19445"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19445"},{"url":"https://access.redhat.com/errata/RHSA-2026:74867"},{"url":"https://access.redhat.com/errata/RHSA-2026:77028"},{"url":"https://access.redhat.com/errata/RHSA-2026:77020"},{"url":"https://access.redhat.com/errata/RHSA-2026:77018"},{"url":"https://access.redhat.com/errata/RHSA-2026:85239"},{"url":"https://access.redhat.com/errata/RHSA-2026:89742"},{"url":"https://access.redhat.com/errata/RHSA-2026:77017"},{"url":"https://access.redhat.com/errata/RHSA-2026:77021"},{"url":"https://access.redhat.com/errata/RHSA-2026:87400"},{"url":"https://access.redhat.com/errata/RHSA-2026:82939"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat"],"cvssSource":"cna","epss":0.00524,"epssPercentile":0.44292,"exploits":{"github":1,"githubRepos":["https://github.com/abraxas/cve-2026-19445-sni-uaf"],"checkedAt":"2026-10-27T17:01:20.502Z"},"exploitAvailable":true,"ingestedAt":"2026-09-30T17:13:20.841Z","patched":["hardened_images"],"scores":{"cna":9.2,"vendor":8.1},"slug":"CVE-2026-19445","body":"## Overview\n\nA 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:74867** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-10-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:74867)\n- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 7 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-19445.json)\n- **RHSA-2026:77028** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-10-07 · [advisory](https://access.redhat.com/errata/RHSA-2026:77028)\n- **RHSA-2026:77020** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-10-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:77020)\n- **RHSA-2026:77018** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-10-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:77018)\n- **RHSA-2026:85239** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux BaseOS (v. 8) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:85239)\n- **RHSA-2026:89742** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-10-26 · [advisory](https://access.redhat.com/errata/RHSA-2026:89742)\n- **RHSA-2026:77017** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-10-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:77017)\n- **RHSA-2026:77021** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-10-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:77021)\n- **RHSA-2026:87400** · Red Hat · fixed in: Red Hat Cost Management On-Premise 1 · released 2026-10-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:87400)\n- **RHSA-2026:82939** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-10-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:82939)","depth":"abyssal","depthScore":63,"depthScoreParts":{"impact":50.6,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":215043,"id":"CVE-2026-19445","ts":1790971582846,"field":"exploit_available","old":"false","new":"true"}]}