CMAKE_TLS_VERIFY

Specify the default value for the file(DOWNLOAD) and file(UPLOAD) commands' TLS_VERIFY options. If this variable is not set, the commands check the CMAKE_TLS_VERIFY environment variable. If neither is set, the default is off.

This variable is also used by the ExternalProject and FetchContent modules for internal calls to file(DOWNLOAD).

TLS verification can help provide confidence that one is connecting to the desired server. When downloading known content, one should also use file hashes to verify it.

set(CMAKE_TLS_VERIFY TRUE)