FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0,freerdp_bitmap_decompress_planar does not validate nSrcWidth/nSrcHeight against planar->maxWidth/maxHeight before RLE decode. 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.