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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2026-66339

This allows the destination server to capture proxy credentials, leading to information disclosure.

MEDIUM 6.5EPSS 0.23%

Does this matter?

Lower severity and a low EPSS score (0.23%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1
6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
EPSS
0.23% probability · 13th percentile
CISA KEV
Not listed
Weakness
CWE-201
Affected
gnome/libsoup · redhat/enterprise linux
Source
secalert@redhat.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.