CVE-2026-121737: Facebook proxygen · Use After Free
Affects Facebook proxygenSource CVE Database V5
Not known to be exploited : upgrade to v2026.11.09.00 soon.
Data as of 11 Nov 2026, 17:30 UTC
Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD
Thin evidence
One scorer or none- Patch
- Available – fixed in v2026.11.09.00
Exploitation evidence
Disclosed: evidence found.
CVE published 11 Nov 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 11 Nov 2026.
What to do
Upgrade Facebook proxygen to v2026.11.09.00.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Facebookproxygen | Affected
| Fixed in
|
AI-suggested
A fix is available in proxygen version v2026.11.09.00. Users should upgrade to this version or later to remediate the vulnerability. No other mitigation or workaround is indicated.
Description
CVE-2026-121737 is a use-after-free vulnerability in Facebook's proxygen HTTP library. It occurs when an unauthenticated HTTP/1.1 client pipelines a second request and then stops reading, causing proxygen's coroutine-based HTTP session to free the pipelined stream during a write timeout reset and subsequently use the freed memory. This can crash the server, resulting in denial of service, and may lead to memory corruption with further impact. The issue affects proxygen versions prior to v2026.11.09.00.