CVE-2026-66339: Gnome Libsoup

Medium severity, CVSS 6.5. EPSS: 0.2% chance of exploitation in the next 30 days.

A flaw was found in libsoup. After a CONNECT tunnel is established through an HTTP proxy, libsoup incorrectly attaches the Proxy-Authorization header to subsequent HTTPS requests sent through that tunnel to the destination server. This allows the destination server to capture proxy credentials, leading to information disclosure.

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 2026-07-24. Last modified 2026-08-24.