🛡️ OESA-2026-1731 — pyopenssl

🔴 CVSS 9.5 — Critical ✅ No Known Exploit OSV
9.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

pyOpenSSL security update

pyOpenSSL is a rather thin wrapper around (a subset of) the OpenSSL library. With thin wrapper we mean that a lot of the object methods do nothing more than calling a corresponding function in the OpenSSL library.

Security Fix(es):

A security vulnerability exists in the PyOpenSSL library's set_tlsext_servername_callback function. When a user-provided callback function raises an unhandled exception, the connection would still be accepted. If a user relies on this callback for any security-sensitive behavior (such as server name-based access control or certificate validation), this vulnerability could allow the security mechanism to be bypassed, potentially permitting unauthorized connections or access.(CVE-2026-27448)

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to set_cookie_generate_callback returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.(CVE-2026-27459)

Affected software

OESA-2026-1731 is recorded against 1 package.

  • pyopenssl (fixed in 24.0.0-3.oe2403sp3)

Timeline and source

Published on 27 March 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

www.openeuler.org (Advisory)
nvd.nist.gov (Advisory)
nvd.nist.gov (Advisory)

Details

Severity CRITICAL
CVSS Score 9.5
CVSS Vector N/A
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-03-27
Updated 2026-08-12
Modified 2026-03-27
Fix URL N/A

Affected Packages

Software From version Fixed in
pyopenssl — 24.0.0-3.oe2403sp3

Similar Threats

Exploit Protection

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