Hi,

The following vulnerability was published for libsoup3.

CVE-2026-15711[0]:
| A vulnerability was found in libsoup's WebSocket frame parsing
| implementation. The library fails to validate length rules specified
| in RFC 6455 §5.5, which mandates that all WebSocket control frames
| (e.g., PING, PONG, CLOSE) contain a payload of 125 bytes or less. A
| remote, unauthenticated attacker can exploit this by sending a non-
| compliant, oversized control frame. Because the parser handles this
| protocol violation improperly instead of throwing an immediate
| connection termination error, it triggers a internal processing
| crash, resulting in a remote denial of service (DoS) for
| applications utilizing libsoup WebSockets.


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-2026-15711
https://www.cve.org/CVERecord?id=CVE-2026-15711
[1] https://gitlab.gnome.org/GNOME/libsoup/-/issues/515

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore