An authenticated attacker can supply an AlternateShell value that xrdp-sesman executes with /bin/sh -c during session start. The unsanitized input allows arbitrary shell commands to run with the privileges of the connected user. This is a classic command injection flaw (CWE‑78) that can compromise the entire remote desktop session before the window manager launches.

The vulnerability is present in neutrinolabs xrdp versions up to and including 0.10.5. All installations that use the default AllowAlternateShell setting, which is enabled when not explicitly configured, are affected. The issue is resolved starting with xrdp 0.10.6.

The CVSS score of 6.3 indicates moderate severity, but the vulnerability provides a clear remote command‑execution path for any authenticated RDP user. EPSS data is not available, and the vulnerability is not listed in CISA’s KEV catalog. The likely attack vector requires the attacker to first authenticate to the RDP service; after authentication, the attacker can exploit the flaw to run arbitrary commands under the privileges of the authenticated user on the server.