CVE-2026-56297

A flaw was found in FreeRDP. A malicious Remote Desktop Protocol (RDP) server can exploit a use-after-free vulnerability due to improper synchronization of channel callback access. By sending DYNVC_DATA and DYNVC_CLOSE messages concurrently, a race condition can be triggered in the drdynvc client thread, leading to heap-use-after-free. This could potentially enable remote code execution or cause a denial of service.

This Moderate impact flaw in FreeRDP allows a malicious RDP server to trigger a use-after-free condition on the client by exploiting a race condition during dynamic virtual channel closure. This could lead to remote code execution or denial of service on the client system when connecting to a compromised or untrusted RDP server.

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.

Configure host-based firewalls (e.g., firewalld) or network egress filtering so that the workstation can only initiate outbound RDP connections (typically TCP 3389) to known, trusted internal RDP gateways or corporate servers. Blocking outbound RDP to the wider internet neutralizes the threat of users accidentally connecting to malicious external endpoints.