The vulnerability in GnuTLS (CVE-2026-42011) arises because permitted name constraints are incorrectly ignored if previous Certificate Authorities only had excluded name constraints. This results in a security bypass during certificate validation, allowing remote attackers to circumvent critical name constraint checks. The issue is part of a set of certificate validation flaws fixed in updated GnuTLS packages. Red Hat has released patches for Red Hat Enterprise Linux 7 Extended Lifecycle Support addressing this and related vulnerabilities. The CVSS 3.1 vector indicates network attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, and high impact on confidentiality and integrity.

Exploitation of this vulnerability allows an attacker to bypass name constraint checks during TLS certificate validation, potentially leading to acceptance of invalid or malicious certificates. This can enable spoofing or man-in-the-middle attacks against affected systems, compromising confidentiality and integrity of communications. The vulnerability does not affect availability. Red Hat classifies the security impact as Moderate in their advisory, but the CVSS score is high due to the potential for significant confidentiality and integrity breaches.

Red Hat has released official security updates for GnuTLS in Red Hat Enterprise Linux 7 Extended Lifecycle Support that address this vulnerability (RHSA-2026:43575). Applying these updates will remediate the issue. Users should follow Red Hat's guidance at https://access.redhat.com/articles/11258 to apply the patches. No additional mitigation is required beyond applying the official fixes.