Bug#1142836: libsoup3: CVE-2026-12478

[Salvatore Bonaccorso]

Source: libsoup3
Version: 3.6.6-1
Severity: important
Tags: security upstream
Forwarded: https://gitlab.gnome.org/GNOME/libsoup/-/merge_requests/518
X-Debbugs-Cc: carnil at debian.org, Debian Security Team <team at security.debian.org>

Hi,

The following vulnerability was published for libsoup3.

CVE-2026-12478[0]:
| The fix for CVE-2026-0716 (commit 6ff7ef0, libsoup 3.6.6) placed the
| integer overflow guard inside the if (masked) block, leaving
| unmasked server-to-client frames unprotected. A malicious WebSocket
| server can send a crafted unmasked frame with a payload length near
| UINT64_MAX to trigger an OOB read in a libsoup-based client when
| max_incoming_payload_size is set to 0.


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-2026-12478
    https://www.cve.org/CVERecord?id=CVE-2026-12478
[1] https://gitlab.gnome.org/GNOME/libsoup/-/merge_requests/518

Regards,
Salvatore