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Vulnerabilities CVE-2026-12151

CVE-2026-12151

High
Open
TLP:CLEAR

undici WebSocket client vulnerable to denial of service via fragment count bypass

NVD CVE.org
Ransomware Critical Infrastructure DDoS

AI Analysis

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Description

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.

Details

CVSS Score
7.5
EPSS Score
0.79%

53.2th percentile

CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Confidence
90%
Published
Jun 17, 2026
Last Modified
Aug 17, 2026
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