Log in Start free

Vulnerability · Published Aug 19, 2026 · Assigned by GitHub_M

CVE-2026-55564FreeRDP: Out-of-bounds read in glyph_cache_get via crafted glyph fragments

Medium 5.4

In plain English

A medium-severity out-of-bounds read in FreeRDP from FreeRDP. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.3%top 74.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12freerdp2no fix listedDEBIAN-CVE-2026-55564
Debian:13freerdp3no fix listedDEBIAN-CVE-2026-55564
Debian:14freerdp33.27.0+dfsg-1DEBIAN-CVE-2026-55564
Ubuntu:22.04:LTSfreerdp2no fix listedUBUNTU-CVE-2026-55564
Ubuntu:24.04:LTSfreerdp33.30.0+dfsg-0ubuntu0.24.04.1USN-8561-1
Ubuntu:24.04:LTSfreerdp33.30.0+dfsg-0ubuntu0.24.04.1UBUNTU-CVE-2026-55564
Ubuntu:25.10freerdp3no fix listedUBUNTU-CVE-2026-55564
Ubuntu:26.04:LTSfreerdp33.30.0+dfsg-0ubuntu0.26.04.1USN-8561-1
Ubuntu:26.04:LTSfreerdp33.30.0+dfsg-0ubuntu0.26.04.1UBUNTU-CVE-2026-55564

Affected products (as reported)

VendorProductVersions
FreeRDP FreeRDP < 3.27.0

Weakness: CWE-125, CWE-193 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L

References