- Add -k on its own line (I didn’t have a .curlrc file, so the entire file is just -k with a newline, of course)
- Run your brew install/upgrade and it should download from mirrors.edge.kernel.org or any other sites with SSL certificate issues
-K, --config <file> Specify a text file to read curl arguments from. The command line arguments found in the text file will be used as if they were provided on the command line.
via. curl - How To Use