CVE-2026-91095 Use after free in proxygen
A use-after-free vulnerability in proxygen's WebTransport stream handling allows attackers to potentially execute arbitrary code or cause denial of service.
- 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-2026-91095?
CVE-2026-91095 is a medium-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, the HTTPTransaction::onWebTransportUniStream and HTTPTransaction::onWebTransportBidiStream APIs could return stream handles that the stream handler had already freed. HQSession then installed those handles as transport read callbacks, which could lead to use of freed memory.
Weakness: CWE-416
Which versions are affected by CVE-2026-91095?
How do I fix CVE-2026-91095?
No fix has been published for CVE-2026-91095 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-2026-91095 being exploited?
There is no known exploitation of CVE-2026-91095 in the wild and no public exploit code.
Sources
Also known as GHSA-c3mh-7h6x-xh3f.