CVE-2025-11677

Use After Free in libwebsockets WebSocket server

State: Published
Severity: 6.3 Medium
Published: Oct 20, 2025
Updated: Oct 24, 2025
Reserved: Oct 13, 2025

Description

Use After Free in WebSocket server implementation in lws_handshake_server in warmcat libwebsockets may allow an attacker, in specific configurations where the user provides a callback function that handles LWS_CALLBACK_HTTP_CONFIRM_UPGRADE, to achieve denial of service.

Scores

CVSS	Score	Vector	Source
4.0	6.3 Medium	CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N	Nozomi

Weaknesses

CWE-416 Use After Free

Affected Products

Product	Versions
libwebsocketswarmcat	3 through 4.4.1,4.3.6Affected

References

https://libwebsockets.org/git/libwebsockets/commit?id=2f082ec31261f556969160143ba94875d783971apatchvendor-advisory
https://www.nozominetworks.com/labs/vulnerability-advisories-cve-2025-11677third-party-advisory

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.