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 original ssl.SSLContext alive. Typical
cases are servers that create an SSLContext per connection or replace it
while connections are open; servers that wrap their listening socket with
it are not affected.


Mitigation: keep a reference to every SSLContext that sets sni_callback for
the lifetime of the server. TLS clients are not affected.

Project Subscriptions

Vendors Products
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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4827-1 python3.11 security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 10 Nov 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Tue, 10 Nov 2026 13:30:00 +0000

Type Values Removed Values Added
References

Tue, 06 Oct 2026 12:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat hummingbird
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics threat_severity

None

cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important


Thu, 01 Oct 2026 01:15:00 +0000


Wed, 30 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
First Time appeared Python
Python cpython
Vendors & Products Python
Python cpython

Wed, 30 Sep 2026 21:00:00 +0000


Wed, 30 Sep 2026 19:30:00 +0000

Type Values Removed Values Added
References

Wed, 30 Sep 2026 16:45:00 +0000

Type Values Removed Values Added
Description 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 original ssl.SSLContext alive. Typical cases are servers that create an SSLContext per connection or replace it while connections are open; servers that wrap their listening socket with it are not affected. Mitigation: keep a reference to every SSLContext that sets sni_callback for the lifetime of the server. TLS clients are not affected.
Title Use-after-free of a server-side SSLContext when sni_callback switches contexts
Weaknesses CWE-416
References
Metrics cvssV4_0

{'score': 9.2, '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: PSF

Published:

Updated: 2026-11-10T12:40:55.732Z

Reserved: 2026-08-10T13:31:21.724Z

Link: CVE-2026-19445

cve-icon Vulnrichment

Updated: 2026-09-30T18:09:39.735Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-30T17:16:45.720

Modified: 2026-11-10T13:18:30.197

Link: CVE-2026-19445

cve-icon Redhat

Severity : Important

Publid Date: 2026-09-30T16:16:04Z

Links: CVE-2026-19445 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-30T21:15:14Z

Weaknesses