Use after free in Meta proxygen
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA.
Summary
In proxygen from v2024.10.28.00 until v2026.09.28.00, WebTransportImpl::terminateSessionStreams (WebTransportImpl::destroy in releases before v2025.08.18.00) failed to unregister read callbacks for streams that were no longer open before destroying them. The transport could then invoke a read callback that had been freed.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA proxygen (Facebook) Fixed in v2026.09.28.00
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
Facebook proxygen v2026.09.28.00
3 records Highest priority Priority LOW 3 LOW
Other records, highest priority first
- TI-2026-58357 Use after free in Meta proxygenPriority LOW 37
- TI-2026-61879 Use after free in Meta proxygenPriority LOW 30
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-91096
- 2026-10-03 Alias added: GHSA-8mv4-xrj3-xg7m
References
More Meta vulnerabilities
- TI-2025-34861 Deserialization of untrusted data in Meta react-server-dom-webpack KEVCVSS 3.1CRITICAL 10.0
- TI-2019-02633 Heap-based buffer overflow in Meta WhatsApp for Android KEVCVSS 3.1CRITICAL 9.8
- TI-2019-13416 Cross-site scripting in Meta WhatsApp Desktop KEVCVSS 3.1HIGH 8.2
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2025-34857 Incorrect authorization in Meta WhatsApp Desktop for Mac KEVCVSS 3.1MEDIUM 5.4
- TI-2025-34863 Deserialization of untrusted data in Meta react-server-dom-webpack CVSS 3.1HIGH 7.5
Sources
- CVE-2026-91096 · CVE Program
- CVE-2026-91096 · NVD
- FIRST EPSS
- GHSA-8mv4-xrj3-xg7m · GitHub Advisory Database · CC BY 4.0
- CVE-2026-91096 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences