PT-2026-27302 · Airtower Luna · Mod-Gnutls

Published

2026-03-24

·

Updated

2026-03-24

·

CVE-2026-33307

CVSS v3.1

7.5

High

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Mod gnutls is a TLS module for Apache HTTPD based on GnuTLS. In versions prior to 0.12.3 and 0.13.0, code for client certificate verification imported the certificate chain sent by the client into a fixed size gnutls x509 crt t x509[] array without checking the number of certificates is less than or equal to the array size. gnutls x509 crt t is a typedef for a pointer to an opaque GnuTLS structure created using with gnutls x509 crt init() before importing certificate data into it, so no attacker-controlled data was written into the stack buffer, but writing a pointer after the last array element generally triggered a segfault, and could theoretically cause stack corruption otherwise (not observed in practice). Server configurations that do not use client certificates (GnuTLSClientVerify ignore, the default) are not affected. The problem has been fixed in version 0.12.3 by checking the length of the provided certificate chain and rejecting it if it exceeds the buffer length, and in version 0.13.0 by rewriting certificate verification to use gnutls certificate verify peers(), removing the need for the buffer entirely. There is no workaround. Version 0.12.3 provides the minimal fix for users of 0.12.x who do not wish to upgrade to 0.13.0 yet.

Fix

Stack Overflow

Weakness Enumeration

CWE-121

Related Identifiers

CVE-2026-33307

Affected Products

Mod-Gnutls