Vulnerability · Published Sep 28, 2026 · Assigned by Meta
CVE-2026-91095
Medium 5.3
In plain English
A medium-severity use-after-free in proxygen from Facebook. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities).
Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.2%top 83.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
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.
Affected products (as reported)
Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
References
- https://www.facebook.com/security/advisories/cve-2026-91095 x_refsource_CONFIRM
- https://github.com/facebook/proxygen/commit/479eb5574195764e80e6cedebef669f6baa85083 x_refsource_MISC