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Advisory record · GHSA-vp96-hxj8-p424

pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback

CVSS 1.7 LowEPSS 0.0026 · 17th percentile

Published by the GitHub Advisory Database at 16 Mar 2026, 15:15 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
pyopensslPyPI>=0.14.0, <26.0.026.0.0
Identifiers
GHSA-vp96-hxj8-p424 · CVE-2026-27448 · PYSEC-2026-2268
Weakness (CWE)
CWE-636
Tags
Published
16 Mar 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

pyOpenSSL versions 0.14.0 up to but not including 26.0.0 are affected. If a user-provided callback passed to set_tlsext_servername_callback raised an unhandled exception, the connection was accepted, which could bypass any security-sensitive checks the callback performed. Upgrade to pyOpenSSL 26.0.0, which rejects connections when the callback raises an unhandled exception.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
1.7 Low 4.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0026, the 17th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:11 UTC First seen by agentprime
  2. 31 Oct 2026, 14:11 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.