CVE-2026-123862 Node.js is vulnerable to a zlib denial of service via a stream destroy during a pending params() call
A peer disconnecting during zlib streaming can crash Node.js processes that call deflate.params() while streaming.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Harmful if only installed
- No
- Needs a specific call
- Yes
- Fix
- Available
What is CVE-2026-123862?
CVE-2026-123862 is a low-severity denial of service vulnerability in nodejs node, published on 11 Nov 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-248
Which versions are affected by CVE-2026-123862?
An affected version is only exploitable if your software calls zlib.params() or deflate.params(). Many projects that include it are not exposed.
How do I fix CVE-2026-123862?
No fix published yet.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-123862 being exploited?
There is no known exploitation of CVE-2026-123862 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-123862, BELL-CVE-2026-123862, DEBIAN-CVE-2026-123862, GHSA-827v-4jh3-rppr, UBUNTU-CVE-2026-123862.