CVE-2026-23531 FreeRDP has heap-buffer-overflow in clear_decompress
A malicious RDP server can trigger a heap buffer overflow in FreeRDP clients, causing crashes or potential code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-23531?
CVE-2026-23531 is a high-severity memory corruption vulnerability in Freerdp Freerdp, published on 19 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-122
Which versions are affected by CVE-2026-23531?
It affects 1 product.
Products include Freerdp Freerdp.
How do I fix CVE-2026-23531?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-23531 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-23531 exists.
Other vulnerabilities in Freerdp Freerdp
- CVE-2021-37594 Other in n/a
- CVE-2021-37595 Other in n/a
- CVE-2026-67305 FreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr
- CVE-2026-66402 FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass
- CVE-2026-67289 FreeRDP before 3.29.0 HTTP Proxy Request Injection via Redirection
Sources
Also known as DEBIAN-CVE-2026-23531, GHSA-xj5h-9cr5-23c5, MINI-vxg7-m9mp-c25h, UBUNTU-CVE-2026-23531.