CVE-2026-30852
Caddy: vars_regexp double-expands user input, leaking env vars and files
Caddy is an extensible server platform that uses TLS by default. From version 2.7.5 to before version 2.11.2, the vars_regexp matcher in vars.go:337 double-expands user-controlled input through the Caddy replacer. When vars_regexp matches against a placeholder like {http.request.header.X-Input}, the header value gets resolved once (expected), then passed through repl.ReplaceAll() again (the bug). This means an attacker can put {env.DATABASE_URL} or {file./etc/passwd} in a request header and the server will evaluate it, leaking environment variables, file contents, and system info. This issue has been patched in version 2.11.2.
| CWE | CWE-200 CWE-74 |
| Vendor | caddyserver |
| Product | caddy |
| Published | Mar 7, 2026 |
| Last Updated | Mar 9, 2026 |
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