UBUNTU-CVE-2026-121407: High severity ubuntu/freerdp vulnerability

FreeRDP before 3.32.2 contains a denial of service vulnerability in the shadow server's remdeskserverthread that allows authenticated clients to crash the process via an inverted PDU length check. Attackers can send an 8192-byte remdesk payload declaring an eight-byte PDU length to trigger a fatal StreamSeek assertion, aborting the server and dropping sessions.