---
id: CVE-2026-55564
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, the glyph_cache_get function in libfreerdp/cache/glyph.c checks
  whether index is greater than cache->number instead of greater than or equal
  to it. A malic…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L'
cwe:
  - CWE-125
  - CWE-193
vendor: freerdp
product: freerdp
affected:
  - freerdp < 3.27.0
patched:
  - freerdp 3.27.0
published: '2026-08-19'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:44:08.997'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55564'
references:
  - url: >-
      https://github.com/FreeRDP/FreeRDP/commit/c29324750e3cbcba8761f147b7a5235cc686930f
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/pull/12885'
    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-6xmj-pr98-cx4c'
    label: security-advisories@github.com
  - url: 'https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-55564.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-55564'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2519813'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-55564'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55564'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
epss: 0.0044
epssPercentile: 0.35492
ingestedAt: '2026-09-09T21:22:45.541Z'
---

## Overview

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, the glyph_cache_get function in libfreerdp/cache/glyph.c checks whether index is greater than cache->number instead of greater than or equal to it. A malicious RDP server can use GLYPH_FRAGMENT_USE replay in update_process_glyph_fragments to make the default cache receive index 254 when cache->number is 254, reading one pointer beyond the entries array and dereferencing it as a glyph. This can crash the client and may disclose adjacent heap data. 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** · Moderate · 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-2026-55564.json)