High [CVE-2026-15711] WebSocket remote denial of service via oversized control frame protocol violation

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.

This flaw poses a moderate availability risk to both client and server applications depending on libsoup for WebSocket networking. By failing to drop connections that break core protocol design rules, the library allows low-complexity remote inputs to abruptly terminate the service state machine.

Exploitation requires no authentication or user interaction, allowing any hostile peer on the wire to forcibly disconnect endpoints or crash application wrapper logic by intentionally packing data into a signaling frame. Red Hat severity: Moderate — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Weakness: CWE-770.