What’s Vulnerable › Vulnerabilities

CVE-2026-91095

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-28 · updated 2026-09-30
• Weakness: CWE-416

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 products

• Facebook proxygen: from v2024.10.28.00 before v2026.09.28.00 — fixed in v2026.09.28.00

How to fix

Upgrade to a fixed version: Facebook proxygen v2026.09.28.00. Check the vendor advisory for mitigations.

References

• https://github.com/facebook/proxygen/commit/479eb5574195764e80e6cedebef669f6baa85083
• https://www.facebook.com/security/advisories/cve-2026-91095

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