CVE-2026-30852: caddyserver caddy Injection

Vulnerability summary

CVE-2026-30852 is a high (CVSS 7.5) Injection vulnerability in caddyserver caddy. EPSS estimates a 0.51% chance of exploitation in the next 30 days, higher than 42.2% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 07-03-2026
   PublishedVulnerability first disclosed.
2. 09-03-2026
   Last modifiedVulnerability information updated.

Description

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-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
• CWE-200Exposure of Sensitive Information to an Unauthorized ActorThe product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.