CVE-2026-66338

A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests.

Score

CVSS 3.1 7.2 High

Status

Analyzed - secalert@redhat.com

Published

2026-07-24

Last modified

2026-07-27

Weaknesses

CWE-444

Affected products

• Libsoup (Gnome)
• Enterprise Linux (Redhat)

References

• https://access.redhat.com/security/cve/CVE-2026-66338
• https://bugzilla.redhat.com/show_bug.cgi?id=2506950