Bug 2545937

Summary: CVE-2026-19445 python3.15: Use-after-free of a server-side SSLContext when sni_callback switches contexts [fedora-all]
Product: [Fedora] Fedora Reporter: Srikanth Balasubramanian <sbalasub>
Component: python3.15Assignee: Python Maintainers <python-maint>
Status: CLOSED ERRATA QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: ksurma, mhroncok, python-maint, python-packagers-sig
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["5337ec1f-6905-4942-a83c-22a9673b156c"]}
Fixed In Version: python3.15-3.15.0~rc3-2.fc45 python3.15-3.15.0-1.fc44 python3.15-3.15.0-1.fc43 Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-10-06 14:11:48 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2544138    

Description Srikanth Balasubramanian 2026-10-05 15:15:34 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.
Comment 1 Fedora Update System 2026-10-05 15:43:13 UTC 
FEDORA-2026-23ca7b14fe (python3.15-3.15.0~rc3-2.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-23ca7b14fe
Comment 2 Fedora Update System 2026-10-05 15:43:21 UTC 
FEDORA-2026-ab1400e97a (python3.15-3.15.0~rc3-2.fc45 and python3-docs-3.15.0~rc3-1.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-ab1400e97a
Comment 3 Fedora Update System 2026-10-05 15:43:31 UTC 
FEDORA-2026-a48c050313 (python3.15-3.15.0~rc3-2.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-a48c050313
Comment 4 Fedora Update System 2026-10-06 01:23:07 UTC 
FEDORA-2026-ab1400e97a has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-ab1400e97a`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-ab1400e97a

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 5 Fedora Update System 2026-10-06 01:56:05 UTC 
FEDORA-2026-23ca7b14fe has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-23ca7b14fe`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-23ca7b14fe

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 6 Fedora Update System 2026-10-06 02:25:59 UTC 
FEDORA-2026-a48c050313 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-a48c050313`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-a48c050313

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 7 Fedora Update System 2026-10-06 14:11:48 UTC 
FEDORA-2026-ab1400e97a (python3.15-3.15.0~rc3-2.fc45 and python3-docs-3.15.0~rc3-1.fc45) has been pushed to the Fedora 45 stable repository.
If problem still persists, please make note of it in this bug report.
Comment 8 Fedora Update System 2026-10-12 02:08:37 UTC 
FEDORA-2026-1419522981 has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-1419522981`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-1419522981

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 9 Fedora Update System 2026-10-12 02:37:04 UTC 
FEDORA-2026-f86849b3f6 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-f86849b3f6`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-f86849b3f6

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 10 Fedora Update System 2026-10-20 04:44:10 UTC 
FEDORA-2026-1419522981 (python3.15-3.15.0-1.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.
Comment 11 Fedora Update System 2026-10-20 05:05:40 UTC 
FEDORA-2026-f86849b3f6 (python3.15-3.15.0-1.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.