motionEye (mEye) is an online interface for a piece of software called "motion," which is a video surveillance program with motion detection. Prior to 0.44.0, motionEye accepts the client-controlled meye_username and meye_password_hash cookies as authentication material without server-side session validation. An unauthenticated attacker who knows a target username and corresponding hash can set the cookies manually or cause them to be loaded by submitting blank credentials through the switch-user authentication flow, after which the server authenticates the attacker as that user. The administrator username and password-hash value are stored in /etc/motioneye/motion.conf, which is globally readable by default, allowing a local shell user to obtain reusable administrator credential material. Successful impersonation can enable account lockout, password changes and persistence, data enumeration, data destruction, and data exfiltration. This issue is fixed in version 0.44.0.