CVE-2026-27459

CRITICAL

9.8

Description

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 Details

CVSS v3.1 Score9.8

SeverityCRITICAL

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published3/18/2026

Last Modified3/25/2026

Sourcenvd

Honeypot Sightings0

Affected Products

pyopenssl:pyopenssl

Weaknesses (CWE)

CWE-120

References

https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst(security-advisories@github.com)

https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408(security-advisories@github.com)

https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4(security-advisories@github.com)

IOC Correlations

No correlations recorded

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