Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's HTTP "host" request matcher is documented as case-insensitive, but when configured with a large host list (>100 entries) it becomes case-sensitive due to an optimized matching path. An attacker can bypass host-based routing and any access controls attached to that route by changing the casing of the "Host" header. Version 2.11.1 contains a fix for the issue.