The mv, cp, and rm file utilities exposed within the ExtremeXOS (EXOS) shell environment fail to safely canonicalize paths and follow symbolic links outside of the intended privilege boundary. An attacker with low-privilege CLI access can create a symbolic link that references a privileged filesystem location and then invoke the affected utilities to read, modify, or replace security-critical files outside of their authorized scope. Under certain conditions, this may enable escalation to root-level access and persistent modification of the device software stack. Exploitation is possible remotely by an attacker holding a low-privilege account, or locally via the serial console. Extreme would like to thank Hadrien Barral (Université Gustave Eiffel) and Georges-Axel Jaloyan (French Ministry of the Interior) for responsible disclosure of their findings.

ExtremeXOS (EXOS) uses a challenge-response mechanism to authorize access to the privileged debug-mode function. The challenge value is generated using an insufficiently random source, which under certain conditions may allow an attacker to predict the expected response and activate debug-mode without authorization. Depending on device configuration and version, this may enable escalation to root-level access and persistent modification of the device software stack. Exploitation requires either a valid low-privilege account on the device (remote scenario) or physical serial console access (local scenario). This vulnerability is distinct from CVE-2017-14329, which addressed a different issue involving Python script privileges. Extreme would like to thank Hadrien Barral (Université Gustave Eiffel) and Georges-Axel Jaloyan (French Ministry of the Interior) for responsible disclosure of their findings.