A vulnerability has been identified in Siveillance VMS 2017 R2 (All versions < V11.2a), Siveillance VMS 2018 R1 (All versions < V12.1a), Siveillance VMS 2018 R2 (All versions < V12.2a), Siveillance VMS 2018 R3 (All versions < V12.3a), Siveillance VMS 2019 R1 (All versions < V13.1a). An attacker with network access to port 80/TCP can change user-defined event properties without proper authorization. The security vulnerability could be exploited by an authenticated attacker with network access to the affected service. No user interaction is required to exploit this security vulnerability. Successful exploitation compromises integrity of the user-defined event properties and the availability of corresponding functionality. At the time of advisory publication no public exploitation of this security vulnerability was known.