backpack/crud: OS command injection in Stats::makeCurlRequest via attacker-controlled Host header (pre-auth)

backpack/crud provides Create, Read, Update & Delete (CRUD) functions for Backpack, a collection of Laravel packages that help users build custom administration panels. Prior to 4.1.70, 5.6.2, 6.8.13, and 7.0.36, Backpack\CRUD\Stats::makeCurlRequest in src/Stats.php is reached from BackpackServiceProvider::boot() and constructs a shell command with a URL influenced by the HTTP Host header, which it passes to exec() without adequate shell neutralization. An unauthenticated attacker whose malformed Host value reaches PHP can inject operating-system commands when exec() and curl are available and the 1-in-100 random gate is reached. Repeated requests can reach the random gate. Successful exploitation executes commands as the web-server user, exposing environment secrets, files, and reachable services and permitting data modification or service disruption. Common reverse-proxy Host validation and hardened PHP configurations that disable exec() reduce reachability but do not correct the vulnerable construction. This issue is fixed in versions 4.1.70, 5.6.2, 6.8.13, and 7.0.36.