CORS misconfiguration in the REST API of Network Optix Nx Witness VMS before version 6.1.2, when running in the default Standard security mode, on Linux and Windows allows an unauthenticated remote attacker to steal the session token of an authenticated user and perform Administrator Account Takeover via a malicious cross-origin web page visited by the victim. The High security mode is not affected.Workaround: For existing installations running in Standard security mode, set Access-Control-Allow-Credentials to false via the REST API: PATCH /rest/v2/system/settings with body {"supportedOrigins": "null"}. Alternatively, select High security level during initial setup. Solution: Update to Nx Witness VMS version 6.1.2 or later, in which Access-Control-Allow-Credentials is set to false in the default Standard security configuration.