Vulnerability Description
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, in ClearCodec, when `glyphData` is present, `clear_decompress` calls `freerdp_image_copy_no_overlap` without validating the destination rectangle, allowing an out-of-bounds read/write via crafted RDPGFX surface updates. A malicious server can trigger a client‑side heap buffer overflow, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Freerdp | Freerdp | < 3.21.0 |
Related Weaknesses (CWE)
References
- https://github.com/FreeRDP/FreeRDP/blob/38514dfa5813aa945a86cfbcec279033f8394468Product
- https://github.com/FreeRDP/FreeRDP/releases/tag/3.21.0Release Notes
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-xj5h-9cr5-23c5ExploitVendor Advisory
FAQ
What is CVE-2026-23531?
CVE-2026-23531 is a vulnerability with a CVSS score of 9.8 (CRITICAL). FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, in ClearCodec, when `glyphData` is present, `clear_decompress` calls `freerdp_image_copy_no_overlap` without v...
How severe is CVE-2026-23531?
CVE-2026-23531 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-23531?
Check the references section above for vendor advisories and patch information. Affected products include: Freerdp Freerdp.