unable to access files outside of site account

From within a site account I'm unable to access files outside of the account, and I can't find the WHM setting that manages that. Here's the scenario: account path: /home/mysite/ test file: /home/mysite/public_html/test.php executable app: /usr/local/bin/myapp In my test file I simply check for existence and executability:
Both checks fail. The file definitely exists and is definitely executable. I can run the file from the command line as root, but not as the mysite user. I thought it might be an open_basedir issue, but that is not enabled on the account as far as I can see. For reference, we're running: Operating System: CloudLinux v7.9.0 Product: cPanel & WHM v104.0.7