FreeRDP up to 3.26.x Glyph Cache libfreerdp/cache/glyph.c glyph_cache_get out-of-bounds

Summaryinfo

A vulnerability marked as critical has been reported in FreeRDP up to 3.26.x. Affected is the function glyph_cache_get of the file libfreerdp/cache/glyph.c of the component Glyph Cache. This manipulation causes out-of-bounds. This vulnerability is handled as CVE-2026-55564. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in FreeRDP up to 3.26.x. It has been declared as critical. Affected by this vulnerability is the function glyph_cache_get of the file libfreerdp/cache/glyph.c of the component Glyph Cache. The manipulation with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-55564 since 06/17/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.27.0 eliminates this vulnerability.

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Productinfo

Type

• Remote Access Software

Name

• FreeRDP

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13
• 3.14
• 3.15
• 3.16
• 3.17
• 3.18
• 3.19
• 3.20
• 3.21
• 3.22
• 3.23
• 3.24
• 3.25
• 3.26

License

• open-source

Website

• Product: https://github.com/FreeRDP/FreeRDP/

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