CVE-2026-3099: Gnome Libsoup

High severity, CVSS 7.3. EPSS: 0.5% chance of exploitation in the next 30 days.

A flaw was found in Libsoup. The server-side digest authentication implementation in the SoupAuthDomainDigest class does not properly track issued nonces or enforce the required incrementing nonce-count (nc) attribute. This vulnerability allows a remote attacker to capture a single valid authentication header and replay it repeatedly. Consequently, the attacker can bypass authentication and gain unauthorized access to protected resources, impersonating the legitimate user.

Affected products

• Gnome Libsoup: affected versions not specified
• Red Hat Enterprise Linux: version 6.0 only; version 7.0 only; version 8.0 only; version 9.0 only; version 10.0 only

Published 2026-03-12. Last modified 2026-06-17.