CVE-2026-27448

CVE Details

Release Date:	2026-03-18
Impact:	Moderate	What is this?

Description

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.

See more information about CVE-2026-27448 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	5.4
Vector String:	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Version:	3.1
Attack Vector:	Network
Attack Complexity:	High
Privileges Required:	None
User Interaction:	None
Scope:	Changed
Confidentiality Impact:	Low
Integrity Impact:	Low
Availability Impact:	None

Errata information

Platform	Errata	Release Date
Oracle Linux version 9 (pyOpenSSL)	ELSA-2026-50324	2026-06-24