FreeRDP, a free Remote Desktop Protocol implementation, has a heap‑buffer overflow in the ClearCodec decode path. A malicious RDP server can send specially crafted residual data that triggers out‑of‑bounds writes on the client’s heap. The overflow can cause the client to crash, producing a denial‑of‑service, and may corrupt heap metadata, creating an opportunity for an attacker to execute arbitrary code depending on the memory allocator and surrounding layout.

This vulnerability affects all FreeRDP clients released prior to version 3.21.0. Any system running a legacy FreeRDP client within a remote desktop session is potentially exposed.

The CVSS score of 7.7 indicates a moderate‑high severity, while the EPSS score of less than 1% suggests a currently low exploitation probability. The vulnerability is not listed in CISA’s KEV catalog. The attack vector is remote; an attacker controls the RDP server and can send malicious packets to affect the client. The impact includes crash, denial of service, heap corruption, and potential remote code execution if heap exploitation succeeds.