The Amcrest IP2M-841B V2.520.AC00.18.R, Dahua IPC-XXBXX V2.622.0000000.9.R, Dahua IPC HX5X3X and HX4X3X V2.800.0000008.0.R, Dahua DH-IPC HX883X and DH-IPC-HX863X V2.622.0000000.7.R, Dahua DH-SD4XXXXX V2.623.0000000.7.R, Dahua DH-SD5XXXXX V2.623.0000000.1.R, Dahua DH-SD6XXXXX V2.640.0000000.2.R and V2.623.0000000.1.R, Dahua NVR5XX-4KS2 V3.216.0000006.0.R, Dahua NVR4XXX-4KS2 V3.216.0000006.0.R, and NVR2XXX-4KS2 do not require authentication to access the HTTP endpoint /videotalk. An unauthenticated, remote person can connect to this endpoint and potentionally listen to the audio of the capturing device.
https://www.tenable.com/security/research/tra-2019-36
https://www.dahuasecurity.com/support/cybersecurity/details/627?us
https://us.dahuasecurity.com/wp-content/uploads/2019/08/Cybersecurity_2019-08-02.pdf