Bug#1142845: libsoup3: CVE-2026-66338

[Salvatore Bonaccorso]

Source: libsoup3
Version: 3.6.6-1
Severity: important
Tags: security upstream
Forwarded: https://gitlab.gnome.org/GNOME/libsoup/-/work_items/533
X-Debbugs-Cc: carnil at debian.org, Debian Security Team <team at security.debian.org>

Hi,

The following vulnerability was published for libsoup3.

CVE-2026-66338[0]:
| 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.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2026-66338
    https://www.cve.org/CVERecord?id=CVE-2026-66338
[1] https://gitlab.gnome.org/GNOME/libsoup/-/work_items/533

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore