Uncaught Exception Affecting undici package, versions >=6.7.0 <6.28.1>=7.0.0 <7.29.1>=8.0.0 <8.10.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-UNDICI-19635210
- published6 Sept 2026
- disclosed4 Sept 2026
- creditmanus-use
Introduced: 4 Sep 2026
NewCVE-2026-19534 (opens in a new tab)How to fix?
Upgrade undici to version 6.28.1, 7.29.1, 8.10.2 or higher.
Overview
undici is an An HTTP/1.1 client, written from scratch for Node.js
Affected versions of this package are vulnerable to Uncaught Exception in its WebSocket client, in the form of a TypeError inside a queueMicrotask callback when a server's 101 response carries a Sec-WebSocket-Protocol header the client never requested. An attacker can crash the process by returning a 101 handshake response that names a subprotocol the client did not offer. This requires the application to open a WebSocket without requesting a subprotocol to an attacker-controlled or compromised server, or over plaintext ws:// where a MitM can alter the handshake.