CVE-2026-91095: Use After Free (CWE-416) in Facebook proxygen
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.
AI Analysis
Technical Summary
The vulnerability exists in proxygen's HTTPTransaction::onWebTransportUniStream and HTTPTransaction::onWebTransportBidiStream APIs, which may return stream handles that the stream handler has already freed. Subsequently, HQSession installs these stale handles as transport read callbacks, causing use-after-free conditions (CWE-416). This flaw affects proxygen versions >=2024.10.28.00 and <2026.09.28.00. No CVSS score or exploit in the wild is currently reported, and no patch or remediation details are provided in the source data.
Potential Impact
Use-after-free vulnerabilities can lead to undefined behavior including application crashes or potential memory corruption. However, no active exploitation or detailed impact scenarios are reported. The vulnerability could affect the stability and security of applications using the affected proxygen versions.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or fix information is provided, users should monitor official Facebook/proxygen advisories for updates and apply any forthcoming patches promptly.
CVE-2026-91095: Use After Free (CWE-416) in Facebook proxygen
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 software
proxygen
pkg:github/facebook/proxygenRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability exists in proxygen's HTTPTransaction::onWebTransportUniStream and HTTPTransaction::onWebTransportBidiStream APIs, which may return stream handles that the stream handler has already freed. Subsequently, HQSession installs these stale handles as transport read callbacks, causing use-after-free conditions (CWE-416). This flaw affects proxygen versions >=2024.10.28.00 and <2026.09.28.00. No CVSS score or exploit in the wild is currently reported, and no patch or remediation details are provided in the source data.
Potential Impact
Use-after-free vulnerabilities can lead to undefined behavior including application crashes or potential memory corruption. However, no active exploitation or detailed impact scenarios are reported. The vulnerability could affect the stability and security of applications using the affected proxygen versions.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or fix information is provided, users should monitor official Facebook/proxygen advisories for updates and apply any forthcoming patches promptly.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Meta
- Date Reserved
- 2026-09-14T18:40:39.036Z
- State
- PUBLISHED
Threat ID: 6abad292f7a7c541062fe5b6
Added to database: 09/28/2026, 20:48:18 UTC
Last enriched: 09/28/2026, 21:03:13 UTC
Last updated: 09/29/2026, 01:57:22 UTC
Views: 9
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