Out-of-bounds Read in Freerdp
CVE-2026-55564
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L.
EPSS exploit prediction
EPSS: 0.004 (36.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 36.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.002
Affected products
- Freerdp — versions < 3.27.0
Weakness classification (CWE)
References
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c (Exploit, Mitigation, Vendor Advisory)
- github.com/FreeRDP/FreeRDP/pull/12885 (Patch, Issue Tracking)
- github.com/FreeRDP/FreeRDP/commit/c29324750e3cbcba8761f147b7a5235cc686930f (Patch)
- github.com/FreeRDP/FreeRDP/releases/tag/3.27.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-55564?
- CVE-2026-55564 is a medium-severity vulnerability in Freerdp, classified under Out-of-bounds Read. CVSS score: 5.4/10. Published 2026-08-19.
- How severe is CVE-2026-55564?
- Medium severity. CVSS v3 base score is 5.4 out of 10.