CVE-2026-9675

Impact: The undici WebSocket client enforces maxPayloadSize per-frame but does not enforce the cumulative size of fragmented uncompressed messages. A malicious WebSocket server can stream many small fragments that each pass per-frame validation but collectively exceed the configured limit, causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service. Affected applications are those using the undici WebSocket client (new WebSocket(...)) that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint. This is a regression specific to undici 8.1.0. The 6.25.0 line shipped the equivalent cumulative check from the start and is unaffected. The 7.x line never had the maxPayloadSize feature and is also unaffected. Patches: Upgrade to undici >= 8.5.0. Workarounds: No workaround is available. The fix must be applied through an upgrade.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://cna.openjsf.org/security-advisories.html	Vendor Advisory
https://github.com/nodejs/undici/security/advisories/GHSA-38rv-x7px-6hhq	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

History

25 Jun 2026, 17:46

Type	Values Removed	Values Added
CPE		cpe:2.3:a:nodejs:undici::::::node.js::*
First Time		Nodejs Nodejs undici
References	~~() https://cna.openjsf.org/security-advisories.html -~~	() https://cna.openjsf.org/security-advisories.html - Vendor Advisory
References	~~() https://github.com/nodejs/undici/security/advisories/GHSA-38rv-x7px-6hhq -~~	() https://github.com/nodejs/undici/security/advisories/GHSA-38rv-x7px-6hhq - Vendor Advisory

17 Jun 2026, 20:20

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-17 17:17

Updated : 2026-06-25 17:46

NVD link : CVE-2026-9675

Mitre link : CVE-2026-9675

CVE.ORG link : CVE-2026-9675

JSON object : View

Products Affected

nodejs

undici

CWE

CWE-400

Uncontrolled Resource Consumption

CWE-770

Allocation of Resources Without Limits or Throttling

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