Description
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; redhat: enterprise linux
References2
- access.redhat.com/security/cve/CVE-2026-66339 Vendor Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2506951 ExploitIssue TrackingMitigationVendor Advisory
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - EPSS — exploit probability
- 0% percentile: 16 · as of 14 November 2026
- CWE
- CWE-201
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.