---
id: CVE-2026-91095
title: >-
  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
summary: >-
  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 i…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-416
vendor: Facebook
product: proxygen
affected:
  - proxygen >= v2024.10.28.00 < v2026.09.28.00
published: '2026-09-28'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T20:17:36.470'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91095'
references:
  - url: >-
      https://github.com/facebook/proxygen/commit/479eb5574195764e80e6cedebef669f6baa85083
    label: cve-assign@fb.com
  - url: 'https://www.facebook.com/security/advisories/cve-2026-91095'
    label: cve-assign@fb.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91095.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-91095'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-91095'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-30T19:49:10.823542Z'
epss: 0.00247
epssPercentile: 0.15894
scores:
  nvd: 5.3
  vendor: 7.5
ingestedAt: '2026-09-28T21:20:54.787Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-29 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91095.json)