NODE.JS · CVE-2026-123862 · Runtime
NO FIX YET · SEE WHAT TO DO
Calling deflate.params() on a zlib stream while it is being piped to a peer can throw an internal assertion if the peer disconnects first. The thrown error bypasses normal error handling and terminates the Node.js process, which gives a remote peer a denial of service.
first public Nov 11, 2026 · 1 source
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Only applications that call deflate.params() while streaming compressed data to a peer over a network connection are exposed. The flaw is in Node.js 22.x, 24.x and 26.x, so servers running those versions with such code should look at it. Applications that never call params() on a zlib stream can skip it.
Not affected if no-params-calls, no-zlib-streaming, other-node-versions
Who cares node.js, self-hosted, servers, zlib
node --version and check whether it is a 22.x, 24.x or 26.x release..params( calls on zlib deflate streams that are piped to network connections.An uncatchable exception in the Node.js zlib streaming API lets a peer crash a process by disconnecting while data is being compressed. zlib.params() queues a flush and completes its work in that write's callback; if the stream is destroyed first, as pipeline() does when the peer goes away, Writable still invokes the callback with an error, but the callback ignores its arguments and asserts that the native handle still exists. The handle is gone, so an ERR_INTERNAL_ASSERTION is thrown from inside stream internals and bypasses the stream's error event, the params() callback, and the pipeline() callback, terminating the process. An application is affected only if it calls deflate.params() while streaming to a peer, which is uncommon. This vulnerability affects Node.js 26.x, 24.x, and 22.x.
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