Undici

This is an uncontrolled resource consumption vulnerability (CWE-400) that can lead to Denial of Service (DoS). In vulnerable Undici versions, when interceptors.deduplicate() is enabled, response data for deduplicated requests could be accumulated in memory for downstream handlers. An attacker-controlled or untrusted upstream endpoint can exploit this with large/chunked responses and concurrent identical requests, causing high memory usage and potential OOM process termination. Impacted users are applications that use Undici’s deduplication interceptor against endpoints that may produce large or long-lived response bodies. PatchesThe issue has been patched by changing deduplication behavior to stream response chunks to downstream handlers as they arrive (instead of full-body accumulation), and by preventing late deduplication when body streaming has already started. Users should upgrade to the first official Undici (and Node.js, where applicable) releases that include this patch.

Published: 2026-03-12T20:13:19.571Z
Updated: 2026-03-13T18:04:58.799Z

ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination. The vulnerability exists because: * The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15 * The createInflateRaw() call is not wrapped in a try-catch block * The resulting exception propagates up through the call stack and crashes the Node.js process

Published: 2026-03-12T20:27:05.600Z
Updated: 2026-08-24T12:07:01.301Z

Undici is an HTTP/1.1 client for Node.js. Prior to 7.18.0 and 6.23.0, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation. This vulnerability is fixed in 7.18.0 and 6.23.0.

Published: 2026-01-14T19:07:13.745Z
Updated: 2026-01-22T20:17:20.208Z

ImpactA server can reply with a WebSocket frame using the 64-bit length form and an extremely large length. undici's ByteParser overflows internal math, ends up in an invalid state, and throws a fatal TypeError that terminates the process. Patches Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

Published: 2026-03-12T20:21:57.775Z
Updated: 2026-08-24T12:07:13.078Z

ImpactWhen an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to: * Inject arbitrary HTTP headers * Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch) The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters: // lib/dispatcher/client-h1.js:1121 if (upgrade) { header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n` }

Published: 2026-03-12T20:17:18.984Z
Updated: 2026-03-13T18:06:03.794Z