CVE-2026-121405

A flaw was found in FreeRDP. When serial device redirection is enabled, a malicious Remote Desktop Protocol (RDP) server can send a crafted serial device-control request specifying an excessively large output buffer length. Because FreeRDP fails to limit this buffer length before allocating memory, this issue allows the server to trigger excessive memory consumption, resulting in a Denial of Service (DoS) due to client memory exhaustion or crash.

This vulnerability is rated as having a Moderate impact because exploitation requires a client user to initiate a connection to a rogue or compromised Remote Desktop server, and successful exploitation results in client application termination rather than code execution. In standard Red Hat Enterprise Linux desktop environments, FreeRDP operates as an outbound client connecting to known enterprise endpoints, and serial port redirection is not utilized by default. Consequently, the flaw cannot be triggered unsolicited across the network and requires specific session parameters to be exposed.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.