An low cost CCTV Camera it might have marking tag over it power cable by the indication of 12V input.
An low cost CCTV PSU will come with energy specification plate of 12.5V 1A .
After some personal research I did succeed to learn that CCTV camera this can tolerate plus/minus 10% from the named 12V input.
CCTV system this is a Camera and a video signal monitor, them be in a major distance from its other.
Usually the PSU this gets installed next to the Video monitor or to video recorder device, several meters of cable will follow for the connection with the camera.
Unfortunately Non-branded extension cables for Video and power supply they do not have quality copper within them, the factory use poor quality recycled copper from China, and wires oxidation this is not visible by naked eye.
Most risky electrical parameter this is minus 10% from voltage supply, actual measurement will be 10.8V at the side of the CCTV camera.
In order of you to be at the safe side such of 10.8V this should be the acceptable low-limit at the CCTV camera own power plug.
But this is the theoretical limit, I would never accept something so low, and I will inspect the condition of both, the extension cable and the PSU.