CVE-2025-11677

Use After Free in libwebsockets WebSocket server

Published Oct 20, 2025 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

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

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4373-1 libwebsockets security update
Ubuntu USN Ubuntu USN USN-8024-1 Libwebsockets vulnerabilities
History
Type Values Removed Values Added
First Time appeared Warmcat
Warmcat libwebsockets
Vendors & Products Warmcat
Warmcat libwebsockets
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'}

threat_severity

Low

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Use After Free in libwebsockets WebSocket server
Weaknesses CWE-416
References
Metrics cvssV4_0

{'score': 6.3, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Nozomi
Published
Updated
Oct 24, 2025, 10:54 AM
Reserved
Oct 13, 2025, 9:56 AM
Status
Deferred
Published
Oct 20, 2025, 2:15 PM
Modified
Oct 8, 2026, 10:10 PM
Severity
Low
Public date
Oct 20, 2025, 1:41 PM