{"id":"CVE-2026-19445","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-19445","generatedAt":"2026-10-28T11:20:39.518Z","title":"A remote, unauthenticated TLS client can make a server crash or call through a freed pointer if its sni_callback assigns a different context to SSLSocket.context (the documented way to select a certificate per server name) and nothing else keeps the…","description":"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.","published":"2026-09-30T17:16:46.000Z","lastModified":"2026-10-03T01:17:25.000Z","status":"Awaiting Analysis","sourceIdentifier":"cna@python.org","cvss":{"version":"4.0","score":9.2,"severity":"CRITICAL","vector":"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/M"},"cwe":["CWE-416"],"affected":[],"epss":{"score":0.00524,"percentile":0.44292,"date":"2026-10-27","history":[{"date":"2026-10-01","score":0.00512,"percentile":0.41505}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.52%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-09-30T17:16:46.000Z","detail":{"score":"9.2","severity":"CRITICAL","publishedAt":"2026-09-30T17:16:45.720Z"},"summary":"New CVE, critical severity (CVSS 9.2)."}],"references":[{"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":"cna@python.org"},{"url":"http://www.openwall.com/lists/oss-security/2026/09/30/17","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-19445","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}