Vulnerability · Published Sep 28, 2026 · Assigned by Meta
CVE-2026-84894
High 7.5
In plain English
A high-severity use-after-free in moxygen from Meta Platforms, Inc. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 17% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.3%top 82.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Meta Platforms, Inc | moxygen | b24f8e65cb83ebe5f3880cc4e3a4c8f64e1882f9 – before 004123dd24c30dad6b649163575145f240dabc94 |
Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N