CVE WatchJul 16, 2026

CVE-2026-12151

Impact: The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a li

CVSS

7.5

High

EPSS

0.8%

p52

KEV

—

Exploit Today

0-100

Published: Jun 17, 2026 · Last modified: Jul 16, 2026 · CWE-400 · CWE-770

EPSS · 30d

0.6%EPSS · 30 days0.8%

2026-06-302026-07-16

Technical 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.

Official references

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