CVE-2026-84895: Facebook proxygen · Use After Free
Affects Facebook proxygenSource CVE Database V5
Not known to be exploited · CVSS 7.3 High : upgrade to v2026.09.28.00 soon.
Data as of 12 Nov 2026, 23:24 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in v2026.09.28.00, 2026.09.28.00
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:LExploitation evidence
Disclosed: evidence found.
CVE published 28 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.
What to do
Upgrade proxygen to v2026.09.28.00; facebook/proxygen to 2026.09.28.00.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Facebookproxygen | Affected
| Fixed in
|
GitHubfacebook/proxygenpkg:github/facebook/proxygenOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
CVE-2026-84895 is a use-after-free vulnerability in Facebook's proxygen library affecting versions from 2026.04.06.00 up to but not including 2026.09.28.00. The issue occurs when QuicWtSession::closeSession accesses member fields after the base class method QuicWtSessionBase::closeSession potentially destroys the session object. This can lead to memory corruption and impacts confidentiality, integrity, and availability.