CVE-2026-121387

A flaw was found in FreeRDP. A malicious Remote Desktop Protocol (RDP) server can cause a Denial of Service (DoS) by sending truncated audio packets to a connecting client. Because the audio decoder fails to verify buffer boundaries before processing incoming frames, it attempts to read memory beyond the allocated buffer, causing the client application to crash.

This vulnerability is rated as Moderate severity because exploitation requires an active connection to an untrusted or compromised RDP server, limiting the blast radius to client-side denial of service rather than code execution or host takeover. FreeRDP is primarily utilized within Red Hat environments as a client application to access known enterprise systems. Exposure is constrained to scenarios where an end user connects to a hostile endpoint that attempts to negotiate the vulnerable GSM610 audio channel. Environments that restrict outbound remote desktop traffic to verified internal servers are not at risk.

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.

Avoid establishing remote desktop sessions to untrusted or unverified RDP servers. If connections to external or untrusted endpoints are necessary, disable audio redirection to prevent the client from negotiating the rdpsnd audio channel. When launching the FreeRDP command-line client, ensure sound redirection options such as /sound are omitted. In graphical remote desktop clients (such as Remmina), disable audio output redirection within the connection profile settings.

Caveats: Disabling audio redirection prevents audio output generated on the remote host from being played back on the local workstation.