CVE-2026-12151
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk46th percentile — higher than 46% of all known CVEs
Summary
The undici WebSocket client does not limit the number of message fragments, allowing a malicious server to send many small continuation frames. This causes unbounded memory growth and denial of service (DoS).
Risk Assessment
The organization is vulnerable to a DoS attack that can crash applications using the undici WebSocket client if they are tricked into connecting to an attacker-controlled endpoint.
Recommendation
Upgrade undici to version 6.26.0, 7.28.0, or 8.5.0 (or later) immediately. No workaround is available.
Original NVD description (English source)
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.