In SonicWall SMA100, an unauthenticated Directory Traversal vulnerability in the handleWAFRedirect CGI allows the user to test for the presence of a file on the server.
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-7483
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2019-0018