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.
History

Mon, 23 Mar 2026 18:15:00 +0000

Type Values Removed Values Added
First Time appeared Pyopenssl
Pyopenssl pyopenssl
CPEs cpe:2.3:a:pyopenssl:pyopenssl:*:*:*:*:*:*:*:*
Vendors & Products Pyopenssl
Pyopenssl pyopenssl
Metrics 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'}

cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


Thu, 19 Mar 2026 00:15:00 +0000

Type Values Removed Values Added
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


Wed, 18 Mar 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Wed, 18 Mar 2026 12:15:00 +0000

Type Values Removed Values Added
First Time appeared Pyca
Pyca pyopenssl
Vendors & Products Pyca
Pyca pyopenssl

Tue, 17 Mar 2026 23:45:00 +0000

Type Values Removed Values Added
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.
Title pyOpenSSL DTLS cookie callback buffer overflow
Weaknesses CWE-120
References
Metrics cvssV4_0

{'score': 7.2, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-03-17T23:34:28.483Z

Updated: 2026-03-18T19:52:15.812Z

Reserved: 2026-02-19T17:25:31.100Z

Link: CVE-2026-27459

cve-icon Vulnrichment

Updated: 2026-03-18T19:52:12.530Z

cve-icon NVD

Status : Analyzed

Published: 2026-03-18T00:16:19.273

Modified: 2026-03-25T16:41:28.017

Link: CVE-2026-27459

cve-icon Redhat

Severity : Important

Publid Date: 2026-03-17T23:34:28Z

Links: CVE-2026-27459 - Bugzilla