Bitmask Riseup VPN 0.21.6 contains a local privilege escalation flaw due to improper access controls. When the software is installed with a non-default installation directory off of the system root, the installer fails to properly set ACLs. This allows lower privileged users to replace the VPN executable with a malicious one. When a higher privileged user such as an Administrator launches that executable, it is possible for the lower privileged user to escalate to Administrator privileges.