Uncaught Exception Affecting undici package, versions >=6.25.0 <6.28.1>=7.28.0 <7.29.1>=8.1.0 <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-19635226
- published6 Sept 2026
- disclosed4 Sept 2026
- creditkrsecu
Introduced: 4 Sep 2026
NewCVE-2026-85024 (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 lib/web/websocket/permessage-deflate.js, whose cleanup calls removeAllListeners() on the zlib InflateRaw object, removing the error listener while the stream is still active. An attacker can crash the Node.js process, and repeat the crash on every reconnect to form a crash loop, by sending a permessage-deflate WebSocket message of roughly 130 KB that exceeds the decompressed-payload size limit and contains a malformed DEFLATE block, so the resulting Z_DATA_ERROR has no listener. This requires the application to use undici's WebSocket client or Node's bundled globalThis.WebSocket against an attacker-controlled or compromised WebSocket server.