What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-08-19 · updated 2026-10-26
• Weakness: CWE-125

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 products

• FreeRDP: before 3.27.0 — fixed in 3.27.0

How to fix

Upgrade to a fixed version: FreeRDP 3.27.0. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/commit/c29324750e3cbcba8761f147b7a5235cc686930f
• https://github.com/FreeRDP/FreeRDP/pull/12885
• https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c

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