CVE catalog

CVE-2025-11677

Libwebsockets vulnerabilities

Severity: Medium · CVSS 6.3CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published: Oct 20, 2025, 1:41:10 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.40% · Oct 25, 2026

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.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	libwebsockets	sid	`4.3.5-7`	fixed
Debian	libwebsockets	forky	`4.3.5-7`	fixed
Debian	libwebsockets	trixie	`4.3.5-1+deb13u2`	fixed
Debian	libwebsockets	trixie-security	`4.3.5-1+deb13u3`	fixed
Debian	libwebsockets	bookworm	`4.1.6-3`	vulnerable
Ubuntu	libwebsockets	noble	Not reported	vulnerable
Ubuntu	libwebsockets	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets-dev	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets-evlib-ev	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets-evlib-glib	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets-evlib-uv	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets-test-server	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets-test-server-common	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets19t64	noble	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets	pro	`4.3.2-4`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1build1`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1build2`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1build3`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets	22.04	`4.0.20-2`	vulnerable
Ubuntu	libwebsockets	22.04	`4.0.20-2ubuntu1`	vulnerable
Ubuntu	libwebsockets	22.04	`4.0.20-2ubuntu1.1`	fixed
Ubuntu	libwebsockets	pro	`4.3.2-4`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1build1`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1build2`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1build3`	vulnerable
Ubuntu	libwebsockets	pro	`4.3.3-1.1ubuntu0.1~esm1`	fixed
Ubuntu	libwebsockets	22.04	`4.0.20-2`	vulnerable
Ubuntu	libwebsockets	22.04	`4.0.20-2ubuntu1`	vulnerable
Ubuntu	libwebsockets	22.04	`4.0.20-2ubuntu1.1`	fixed
Ubuntu	libwebsockets	25.10	`4.3.5-1`	vulnerable

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	libwebsockets	source	sid	`4.3.5-3`	not yet assigned	Not reported	[1118747]
Debian	libwebsockets	source	forky	`4.3.5-3`	not yet assigned	Not reported	[1118747]
Debian	libwebsockets	source	trixie	`4.3.5-1+deb13u1`	not yet assigned	Not reported	[1118747]
Debian	libwebsockets	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1118747]
Ubuntu	libwebsockets	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets-dev	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets-evlib-ev	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets-evlib-glib	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets-evlib-uv	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets-test-server	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets-test-server-common	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets19t64	deb	noble	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	Not reported	Not reported
Ubuntu	libwebsockets	deb	pro	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	USN-8024-1	Not reported
Ubuntu	libwebsockets	deb	22.04	`4.0.20-2ubuntu1.1`	Not reported	USN-8024-1	Not reported
Ubuntu	libwebsockets	deb	pro	`4.3.3-1.1ubuntu0.1~esm1`	Not reported	UBUNTU-CVE-2025-11677	Not reported
Ubuntu	libwebsockets	deb	22.04	`4.0.20-2ubuntu1.1`	Not reported	UBUNTU-CVE-2025-11677	Not reported

[Debian bug #1118747]

Notes

[bookworm] libwebsockets: Minor issue

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libwebsockets17]Affected
Source package: [libwebsockets]
Details (2)
- 4.1.6-3 · amd64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
- 4.1.6-3 · arm64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
[libwebsockets-dev]Affected
Source package: [libwebsockets]
Details (2)
- 4.1.6-3 · amd64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
- 4.1.6-3 · arm64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
[libwebsockets-evlib-ev]Affected
Source package: [libwebsockets]
Details (2)
- 4.1.6-3 · amd64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
- 4.1.6-3 · arm64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
[libwebsockets-evlib-glib]Affected
Source package: [libwebsockets]
Details (2)
- 4.1.6-3 · amd64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
- 4.1.6-3 · arm64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
[libwebsockets-evlib-uv]Affected
Source package: [libwebsockets]
Details (2)
- 4.1.6-3 · amd64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
- 4.1.6-3 · arm64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
[libwebsockets-test-server]Affected
Source package: [libwebsockets]
Details (2)
- 4.1.6-3 · amd64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
- 4.1.6-3 · arm64 · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
[libwebsockets-test-server-common]Affected
Source package: [libwebsockets]
Details (2)
- 4.1.6-3 · all · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12
- 4.1.6-3 · all · bookworm
  Affected
  usn · libwebsockets · debian · bookworm; usn · libwebsockets · debian · 12

[Debian 13 (Trixie)]

[libwebsockets19t64]Fixed
Source package: [libwebsockets]
Details (3)
- 4.3.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u3 · amd64 · trixie-security
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
[libwebsockets-dev]Fixed
Source package: [libwebsockets]
Details (3)
- 4.3.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u3 · amd64 · trixie-security
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
[libwebsockets-evlib-ev]Fixed
Source package: [libwebsockets]
Details (3)
- 4.3.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u3 · amd64 · trixie-security
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
[libwebsockets-evlib-glib]Fixed
Source package: [libwebsockets]
Details (3)
- 4.3.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u3 · amd64 · trixie-security
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
[libwebsockets-evlib-uv]Fixed
Source package: [libwebsockets]
Details (3)
- 4.3.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u3 · amd64 · trixie-security
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
[libwebsockets-test-server]Fixed
Source package: [libwebsockets]
Details (3)
- 4.3.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u3 · amd64 · trixie-security
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
[libwebsockets-test-server-common]Fixed
Source package: [libwebsockets]
Details (3)
- 4.3.5-1+deb13u1 · all · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u1 · all · trixie
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13
- 4.3.5-1+deb13u3 · all · trixie-security
  Fixed · Fixed: 4.3.5-1+deb13u1
  usn · libwebsockets · debian · 13

Observed: Oct 27, 2026, 11:26:08 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [Ubuntu Security Notices (USN)]