CVE-2026-23531 — FreeRDP has heap-buffer-overflow in clear_decompress

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
FreeRDP / FreeRDP	affected < 3.21.0

CWE

CWE-122

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in FreeRDP. A malicious server can exploit an out-of-bounds read/write vulnerability in the ClearCodec component by sending crafted RDPGFX surface updates. This can trigger a client-side heap buffer overflow, leading to a crash (Denial of Service (DoS)) and potential heap corruption with a risk of arbitrary code execution. For this vulnerability to be exploited, a client must connect to a maliciously-configured server.