CVE-2026-48126 Algernon: Host header path traversal in --domain mode reads files and runs Lua from parent dir

Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain or --letsencrypt, which silently turns on --domain at engine/flags.go:372, the request handler resolves the served directory by joining the configured --dir with the value of the...