Description

Security researchers have uncovered critical security weaknesses in InputPlumber, a Linux component used to aggregate physical input devices into virtual controllers, commonly deployed in gaming-focused environments such as SteamOS. The flaws allow unprivileged local users to interact with sensitive system services without proper authorization, enabling malicious input injection and system disruption. The root cause lies in insufficient access control on InputPlumber’s system-level D-Bus interface, exposing high-risk functionality to any local account. If exploited, these issues could allow attackers to manipulate active user sessions, interfere with system stability, or access sensitive operational details. The vulnerability primarily affects the org.shadowblip.InputManager D-Bus service, where authentication checks were either missing or incorrectly enforced in affected versions. Two exposed methods present notable risk. The first allows the creation of composite input devices using attacker-supplied file paths, which can be abused to probe for restricted files or exhaust system resources, resulting in denial-of-service conditions. The second permits the creation of virtual keyboard devices, effectively enabling attackers to inject keystrokes into graphical or console sessions. This capability could be leveraged to execute commands within a logged-in user’s context or manipulate applications without user interaction. The security impact is amplified by the local attack surface, as no elevated privileges are required to trigger the vulnerable functionality. Systems running InputPlumber versions prior to 0.69.0 are particularly exposed, especially those used in multi-user or shared environments. In response, maintainers have introduced stricter Polkit-based authorization and additional hardening measures to restrict access to sensitive D-Bus methods. Organizations and users relying on InputPlumber should prioritize upgrading to patched releases, validate authorization policies, and limit access to input-related system services to reduce the risk of exploitation.