The Grandstream UCM6200 series before 1.0.20.22 is vulnerable to an SQL injection via the HTTP server's websockify endpoint. A remote unauthenticated attacker can invoke the login action with a crafted username and, through the use of timing attacks, can discover user passwords.
The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.