CVE-2025-11677 | Nozomi Networks Labs

Summary

Use After Free in WebSocket server implementation in lws_handshake_server in warmcat libwebsockets.

Impact

It 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.

Issue Date

October 8, 2025

Affects

This issue affects libwebsockets from (including) 3 and up to (including) 4.3.6, 4.4.1

CVE Name

CVE-2025-11677

CVSS Details

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

CVSS Score

6.3

Solution

Update the library to its latest stable release, if not possible backport the fix commit 2f082ec31261f556969160143ba94875d783971a

Mitigations

Acknowledgements

Raffaele Bova of Nozomi Networks

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