---
id: CVE-2026-23534
title: FreeRDP is a free implementation of the Remote Desktop Protocol
summary: >-
  FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to
  version 3.21.0, a client-side heap buffer overflow occurs in the ClearCodec
  bands decode path when crafted band coordinates allow writes past the end of
  the destin…
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-122
vendor: freerdp
product: freerdp
affected:
  - freerdp < 3.21.0
patched:
  - freerdp 3.21.0
published: '2026-01-19'
updated: '2026-06-30'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-23534'
references:
  - url: >-
      https://github.com/FreeRDP/FreeRDP/blob/38514dfa5813aa945a86cfbcec279033f8394468/libfreerdp/codec/clear.c#L878-L879
    label: security-advisories@github.com
  - url: >-
      https://github.com/FreeRDP/FreeRDP/blob/38514dfa5813aa945a86cfbcec279033f8394468/libfreerdp/codec/clear.c#L883-L884
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/releases/tag/3.21.0'
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-3frr-mp8w-4599'
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:2048'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:2081'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:2222'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:2736'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:2952'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:3037'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-23534'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2430888'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23534.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.00521
epssPercentile: 0.41745
ingestedAt: '2026-06-30T13:26:50.513Z'
---

## Overview

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, a client-side heap buffer overflow occurs in the ClearCodec bands decode path when crafted band coordinates allow writes past the end of the destination surface buffer. A malicious server can trigger a client‑side heap buffer overflow, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.

## Affected

- `freerdp < 3.21.0`

## Remediation

Upgrade past the affected range:

- `freerdp 3.21.0`