CVE-2026-30852

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-74
• CWE-200

• https://github.com/caddyserver/caddy/pull/5408Issue Tracking, Patch
• https://github.com/caddyserver/caddy/releases/tag/v2.11.2Product, Release Notes
• https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxfExploit, Mitigation, Vendor Advisory

Published

Mar 7, 2026

Last Modified

Jun 17, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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