CVE-2026-30852 (GCVE-0-2026-30852)
Vulnerability from cvelistv5 – Published: 2026-03-07 16:28 – Updated: 2026-03-09 18:24
VLAI
EPSS
VEX
Title
Caddy: vars_regexp double-expands user input, leaking env vars and files
Summary
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.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-09 18:19 UTC
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/caddyserver/caddy/security/adv… | x_refsource_CONFIRM |
| https://github.com/caddyserver/caddy/pull/5408 | x_refsource_MISC |
| https://github.com/caddyserver/caddy/releases/tag… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| caddyserver | caddy |
Affected:
>= 2.7.5, < 2.11.2
|
guessed |
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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