CVE-2026-91096 Details
Description
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.
A use-after-free vulnerability has been identified in Facebook's Proxygen library, specifically in the WebTransport implementation. This issue is present in Proxygen versions 2024.10.28.00 prior to 2026.09.28.00. The vulnerability arises because the 'terminateSessionStreams' method (or 'destroy' in releases before 2025.08.18.00') did not properly unregister read callbacks for streams that had already been closed, before the streams were destroyed. As a result, the transport layer could potentially invoke a read callback for a stream that had been freed, leading to undefined behavior.
Users can update to Proxygen version 2026.09.28.00 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 28, 2026CISA-ADP
Assessed Sep 30, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/facebook/proxygen/commit/479eb5574195764e80e6cedebef669f6baa85083 | [email protected] | Source CodeVendor |
| https://www.facebook.com/security/advisories/cve-2026-91096 | [email protected] | AdvisoryVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-416 | Use After Free | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| Facebook proxygen | >= 2024.10.28.00, < 2026.09.28.00 |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 30, 2026 | CVE Modified | CISA-ADP |
| Sep 28, 2026 | New CVE Received | [email protected] |