---
id: CVE-2026-55191
title: FreeRDP is a free implementation of the Remote Desktop Protocol
summary: >-
  FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to
  3.27.0, FreeRDP clients that negotiate RDPGFX AVC444 with an H.264 decoder
  backend calculate the intermediate YUV444 allocation size in
  libfreerdp/codec/h264.c wit…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
  - CWE-190
  - CWE-787
vendor: freerdp
product: freerdp
affected:
  - freerdp < 3.27.0
patched:
  - freerdp 3.27.0
published: '2026-08-19'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:47:02.713'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55191'
references:
  - url: >-
      https://github.com/FreeRDP/FreeRDP/commit/97f40b9e766af375f4e41ac6a3f4397d708d249c
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/pull/12873'
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0'
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr'
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-55191.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-55191'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2519817'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-55191'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55191'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
epss: 0.00653
epssPercentile: 0.49912
ingestedAt: '2026-09-09T21:22:45.541Z'
scores:
  nvd: 9.8
  vendor: 8.8
---

## Overview

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients that negotiate RDPGFX AVC444 with an H.264 decoder backend calculate the intermediate YUV444 allocation size in libfreerdp/codec/h264.c with 32-bit multiplication in avc444_ensure_buffer. A malicious RDP server can supply surface dimensions for which piDstStride multiplied by padDstHeight wraps to a small nonzero value, causing winpr_aligned_recalloc to allocate an undersized buffer before YUV420CombineToYUV444 writes using the actual stride and rectangle dimensions. This can cause a client crash and may permit code execution through attacker-influenced heap corruption. This issue is fixed in version 3.27.0.

## Affected

- `freerdp < 3.27.0`

## Remediation

Upgrade past the affected range:

- `freerdp 3.27.0`

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-09-22 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-55191.json)