CVE-2026-91096 Use after free in proxygen
Attackers can trigger a use-after-free in proxygen's WebTransport implementation, 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-2026-91096?
CVE-2026-91096 is a high-severity use after free vulnerability in Facebook proxygen, 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 proxygen from v2024.10.28.00 until v2026.09.28.00, WebTransportImpl::terminateSessionStreams (WebTransportImpl::destroy in releases before v2025.08.18.00) failed to unregister read callbacks for streams that were no longer open before destroying them. The transport could then invoke a read callback that had been freed.
Weakness: CWE-416
Which versions are affected by CVE-2026-91096?
How do I fix CVE-2026-91096?
No fix has been published for CVE-2026-91096 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-2026-91096 being exploited?
There is no known exploitation of CVE-2026-91096 in the wild and no public exploit code.
Sources
Also known as GHSA-8mv4-xrj3-xg7m.