undici up to 6.28.0/7.29.0/8.10.1 WebSocket Client null pointer dereference

Summaryinfo

A vulnerability classified as problematic was found in undici up to 6.28.0/7.29.0/8.10.1. Affected is an unknown function of the component WebSocket Client. Executing a manipulation can lead to null pointer dereference. This vulnerability is tracked as CVE-2026-19534. The attack can be launched remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in undici up to 6.28.0/7.29.0/8.10.1. It has been declared as problematic. This vulnerability affects an unknown function of the component WebSocket Client. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. The product dereferences a pointer that it expects to be valid but is NULL. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-19534 since 08/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 352183 (AlmaLinux 10 : nodejs24 (ALSA-2026:73428)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.28.1, 7.29.1 or 8.10.2 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (352183) and CERT Bund (WID-SEC-2026-3640). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Red Hat Enterprise Linux
• RESF Rocky Linux
• Oracle Linux

Productinfo

Name

• undici

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20
• 6.21
• 6.22
• 6.23
• 6.24
• 6.25
• 6.26
• 6.27
• 6.28.0
• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15
• 7.16
• 7.17
• 7.18
• 7.19
• 7.20
• 7.21
• 7.22
• 7.23
• 7.24
• 7.25
• 7.26
• 7.27
• 7.28
• 7.29.0
• 8.10.0
• 8.10.1

CPE 2.3info

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CPE 2.2info

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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