CVE-2026-55564
MediumCVSS 5.4Summary
FreeRDP prior to 3.27.0 has a vulnerability in the glyph_cache_get function in libfreerdp/cache/glyph.c which 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.
Risk Assessment
The risk includes RDP client crashes and potential heap memory disclosure, which could compromise data confidentiality and affect service availability.
Recommendation
It is recommended to upgrade FreeRDP to version 3.27.0 or later, which includes the fix. Also, limit trust in RDP servers and monitor GLYPH_FRAGMENT_USE messages.
Original NVD description (English source)
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.