CVE-2026-84894 Use after free in moxygen
A remote attacker can trigger a use-after-free in the Moxygen library by sending a specific data stream, potentially leading to code execution or crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-84894?
CVE-2026-84894 is a high-severity use after free vulnerability in Meta Platforms, Inc moxygen, published on 28 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In moxygen before commit 004123dd24c3, MoQSession::dataStreamReadLoop keeps using a stream read handle after reading a FIN, which invalidates the handle under proxygen's WebTransport API. A remote peer can trigger the stale use by opening a data stream that names an unknown track alias and carries the FIN in the same write.
Weakness: CWE-416
Which versions are affected by CVE-2026-84894?
How do I fix CVE-2026-84894?
No fix has been published for CVE-2026-84894 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-84894 being exploited?
There is no known exploitation of CVE-2026-84894 in the wild and no public exploit code.
Sources
Also known as GHSA-mqcv-532f-gp47.