CVE catalog

CVE-2026-19534

Severity: High · CVSS 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: Sep 4, 2026, 5:10:05 PM UTC
Updated: Sep 4, 2026, 6:17:51 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.39% · Oct 25, 2026

undici's WebSocket client crashes the whole Node.js process during the opening handshake when a server responds with a subprotocol that the client never requested. A default WebSocket connection sends no subprotocol, but if the server's 101 response includes a Sec-WebSocket-Protocol header, undici dereferences a null value while checking it against the requested list and throws an uncaught TypeError. Because that code runs inside a microtask with no surrounding error handling, the exception propagates and terminates the process under Node's default behavior, instead of gracefully failing the connection as required by the WebSocket protocol. Any application that opens a WebSocket to an attacker-controlled or compromised server, or over a plaintext connection subject to a machine-in-the-middle, can be crashed remotely without authentication in the default configuration. This affects undici versions from 6.7.0 up to 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

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	node-undici	sid	`8.12.2+dfsg+~cs3.2.3-2`	fixed
Debian	node-undici	forky	`8.10.2+dfsg+~cs3.2.2-1`	fixed
Debian	node-undici	trixie	`7.3.0+dfsg1+~cs24.12.11-1`	vulnerable
Debian	node-undici	bookworm	`5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4`	vulnerable
Debian	node-undici	bookworm-security	`5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3`	vulnerable
Cpe	undici	Not reported	`8.10.2`	fixed
Npm	undici	Not reported	`8.10.2`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	node-undici	source	sid	`8.10.2+dfsg+~cs3.2.2-1`	not yet assigned	Not reported	[1146745]
Debian	node-undici	source	forky	`8.10.2+dfsg+~cs3.2.2-1`	not yet assigned	Not reported	[1146745]
Debian	node-undici	source	trixie	`(unfixed)`	not yet assigned	Not reported	[1146745]
Debian	node-undici	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1146745]
Cpe	undici	cpe	Not reported	`8.10.2`	Not reported	NVD-CVE-2026-19534	Not reported
Npm	undici	npm	Not reported	`8.10.2`	Not reported	GHSA-RFGV-XXQX-MFG5	Not reported

[Debian bug #1146745]

Notes

[trixie] node-undici: Minor issue [bookworm] node-undici: Minor issue

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[node-llhttp]Affected
Source package: [node-undici]
Details (4)
- 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12
- 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12
- 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12
- 8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12
[node-undici]Affected
Details (4)
- 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12
- 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 · all · bookworm
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12
- 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12
- 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 · all · bookworm-security
  Affected
  nvd · node-undici · debian · bookworm; nvd · node-undici · debian · 12

[Debian 13 (Trixie)]

[libllhttp9.2]Affected
Source package: [node-undici]
Details (2)
- 9.2.1~7.3.0+dfsg1+~cs24.12.11-1 · amd64 · trixie
  Affected
  nvd · node-undici · debian · 13
- 9.2.1~7.3.0+dfsg1+~cs24.12.11-1 · arm64 · trixie
  Affected
  nvd · node-undici · debian · 13
[libllhttp-dev]Affected
Source package: [node-undici]
Details (2)
- 9.2.1~7.3.0+dfsg1+~cs24.12.11-1 · amd64 · trixie
  Affected
  nvd · node-undici · debian · 13
- 9.2.1~7.3.0+dfsg1+~cs24.12.11-1 · arm64 · trixie
  Affected
  nvd · node-undici · debian · 13
[node-llhttp]Affected
Source package: [node-undici]
Details (2)
- 9.2.1~7.3.0+dfsg1+~cs24.12.11-1 · all · trixie
  Affected
  nvd · node-undici · debian · 13
- 9.2.1~7.3.0+dfsg1+~cs24.12.11-1 · all · trixie
  Affected
  nvd · node-undici · debian · 13
[node-undici]Affected
Details (2)
- 7.3.0+dfsg1+~cs24.12.11-1 · all · trixie
  Affected
  nvd · node-undici · debian · 13
- 7.3.0+dfsg1+~cs24.12.11-1 · all · trixie
  Affected
  nvd · node-undici · debian · 13

Observed: Oct 23, 2026, 9:29:57 PM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]