GHSA-6jxj-px6v-747w - Crass: Deeply nested CSS blocks and functions can trigger a SystemStackError or excessive memory usage

### Impact Crass recursively parses CSS simple blocks and functions without a depth guard. An attacker-controlled value containing many deeply nested blocks can recurse until Ruby raises `SystemStackError: stack level too deep`, or can cause excessive memory usage. ### Patches This is fixed in Crass 1.0.7, which adds a configurable depth limit with a conservative default. ### Workarounds Add `SystemStackError` handling around Crass calls in your application. Buy more RAM.