CVE-2026-121399

A flaw was found in FreeRDP. A malicious Remote Desktop (RD) Gateway server can trigger a Denial of Service (DoS) by sending a specially crafted packet header with an excessively large declared length prior to authentication. This causes the client to allocate an excessive amount of system memory, leading to memory exhaustion and application unresponsiveness.

This vulnerability is classified as having a Moderate impact because exploitation is limited to a client-side denial of service and does not permit remote code execution or data exposure. In Red Hat environments, FreeRDP operates as a client utility, meaning that exploitation requires an interactive user to initiate a connection to an untrusted or compromised Remote Desktop Gateway. While an attacker controlling the gateway can trigger excessive client memory consumption and crash the application prior to authentication, the blast radius is strictly confined to the initiating user's local process.

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.