---
id: CVE-2026-91948
title: >-
  FreeRDP versions before 3.31.0 contain an out-of-bounds write vulnerability in
  server-side static virtual channel handling when CHANNEL_OPTION_SHOW_PROTOCOL
  is enabled
summary: >-
  FreeRDP versions before 3.31.0 contain an out-of-bounds write vulnerability in
  server-side static virtual channel handling when CHANNEL_OPTION_SHOW_PROTOCOL
  is enabled. Authenticated clients can queue oversized channel messages that
  caus…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-191
  - CWE-124
vendor: FreeRDP
product: FreeRDP
affected:
  - FreeRDP >= 3.28.0 < 3.31.0
published: '2026-09-15'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T12:18:29.793'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91948'
references:
  - url: >-
      https://github.com/FreeRDP/FreeRDP/commit/40d9202cd95551600c07437ce6bd5ecd7d31e57b
    label: disclosure@vulncheck.com
  - url: 'https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-9jcm-x588-gh26'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/freerdp-before-3.31.0-out-of-bounds-write-via-show-protocol
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91948.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-91948'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2533904'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-91948'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91948'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-16T03:56:31.656578Z'
epss: 0.0059
epssPercentile: 0.45827
exploitAvailable: true
ingestedAt: '2026-09-15T15:39:12.921Z'
---

## Overview

FreeRDP versions before 3.31.0 contain an out-of-bounds write vulnerability in server-side static virtual channel handling when CHANNEL_OPTION_SHOW_PROTOCOL is enabled. Authenticated clients can queue oversized channel messages that cause buffer underflow and corrupt heap memory including live pointers, potentially enabling code execution.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10 · no fix planned: Red Hat Enterprise Linux 10 · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91948.json)