CVE-2026-55564

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

HIGH
7.1
CVSS Score
Published: August 19, 2026 at 05:45 PM UTC
Updated: October 26, 2026 at 11:10 AM UTC
1 product affected across 1 vendorFreeRDP

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Severity
HIGH7.1
Exploit prediction
EPSS 0.3%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.27.0
Affected range stops below 3.27.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMExploitMitigationVendor Advisory
Source: cverecord
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/FreeRDP/FreeRDP/pull/12885
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-125CWE-193

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