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pyOpenSSL 22.0.x < 26.0.0 Buffer Overflow

critical Nessus Plugin ID 318387

Synopsis

A Python library installed on the remote host is affected by a buffer overflow vulnerability.

Description

The version of pyOpenSSL installed on the remote host is prior to 26.0.0. It is, therefore, affected by a buffer overflow vulnerability:

 - 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)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to pyOpenSSL version 26.0.0 or later.

See Also

http://www.nessus.org/u?420af500

http://www.nessus.org/u?4546c59a

Plugin Details

Severity: Critical

ID: 318387

File Name: pyopenssl_CVE-2026-27459.nasl

Version: 1.1

Type: Local

Agent: windows, macosx, unix

Family: Misc.

Published: 6/3/2026

Updated: 6/3/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Critical

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-27459

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v4

Risk Factor: Critical

Base Score: 9.2

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

Vulnerability Information

CPE: cpe:/a:pyopenssl:pyopenssl

Patch Publication Date: 3/18/2026

Vulnerability Publication Date: 3/18/2026

Reference Information

CVE: CVE-2026-27459

IAVA: 2026-A-0248