CVE-2026-12151
Published:June 17, 2026
Updated:June 21, 2026
Impact:
The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively 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(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.
All releases starting at undici 6.17.0 are affected.
Patches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds:
No workaround is available. The fix must be applied through an upgrade.
Affected Packages
https://github.com/nodejs/undici.git (GITHUB):
Affected version(s) >=v7.0.0 <v7.28.0Fix Suggestion:
Update to version v7.28.0https://github.com/nodejs/undici.git (GITHUB):
Affected version(s) >=v8.0.0 <v8.5.0Fix Suggestion:
Update to version v8.5.0https://github.com/nodejs/undici.git (GITHUB):
Affected version(s) >=v6.17.0 <v6.27.0Fix Suggestion:
Update to version v6.27.0undici (NPM):
Affected version(s) >=0.1.0 <6.27.0Fix Suggestion:
Update to version 6.27.0undici (NPM):
Affected version(s) >=8.0.0 <8.5.0Fix Suggestion:
Update to version 8.5.0undici (NPM):
Affected version(s) >=7.0.0 <7.28.0Fix Suggestion:
Update to version 7.28.0undici (NPM):
Affected version(s) >=6.17.0 <6.27.0Fix Suggestion:
Update to version 6.27.0Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
EPSS
Base Score:
0.28