Resource exhaustion in undici - CVE-2026-9675
Published: June 17, 2026
Vulnerability identifier: #VU134757
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-9675
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Node.js
Affected software:
undici
undici
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the WebSocket client when processing fragmented uncompressed messages. A remote attacker can stream many small WebSocket fragments to cause a denial of service.
Exploitation requires an application using the WebSocket client to connect to an attacker-controlled or compromised WebSocket endpoint.
How to mitigate CVE-2026-9675
Install security update from vendor's website.