{"id":"CVE-2026-30852","summary":"Caddy: vars_regexp double-expands user input, leaking env vars and files","details":"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.","aliases":["GHSA-m2w3-8f23-hxxf","GO-2026-4644"],"modified":"2026-04-10T05:41:56.787562Z","published":"2026-03-07T16:28:26.894Z","related":["SUSE-SU-2026:1042-1"],"database_specific":{"cwe_ids":["CWE-200","CWE-74"],"cna_assigner":"GitHub_M","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/30xxx/CVE-2026-30852.json"},"references":[{"type":"WEB","url":"https://github.com/caddyserver/caddy/releases/tag/v2.11.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/30xxx/CVE-2026-30852.json"},{"type":"ADVISORY","url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxf"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-30852"},{"type":"FIX","url":"https://github.com/caddyserver/caddy/pull/5408"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/caddyserver/caddy","events":[{"introduced":"0e204b730aa2b1fa0835336b1117eff8c420f713"},{"fixed":"ffb6ab0644f24c5ee6542aca6bd59b7a1b0a8f91"}]}],"versions":["v2.10.0","v2.10.0-beta.1","v2.10.0-beta.2","v2.10.0-beta.3","v2.10.0-beta.4","v2.10.1","v2.10.2","v2.11.0","v2.11.0-beta.1","v2.11.0-beta.2","v2.11.1","v2.7.5","v2.8.0","v2.8.0-beta.1","v2.8.0-beta.2","v2.8.0-rc.1","v2.8.1","v2.8.2","v2.8.3","v2.8.4","v2.9.0","v2.9.0-beta.1","v2.9.0-beta.2","v2.9.0-beta.3","v2.9.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-30852.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/mholt/caddy","events":[{"introduced":"0e204b730aa2b1fa0835336b1117eff8c420f713"},{"fixed":"ffb6ab0644f24c5ee6542aca6bd59b7a1b0a8f91"}],"database_specific":{"versions":[{"introduced":"2.7.5"},{"fixed":"2.11.2"}]}}],"versions":["v2.10.0","v2.10.0-beta.1","v2.10.0-beta.2","v2.10.0-beta.3","v2.10.0-beta.4","v2.10.1","v2.10.2","v2.11.0","v2.11.0-beta.1","v2.11.0-beta.2","v2.11.1","v2.7.5","v2.8.0","v2.8.0-beta.1","v2.8.0-beta.2","v2.8.0-rc.1","v2.8.1","v2.8.2","v2.8.3","v2.8.4","v2.9.0","v2.9.0-beta.1","v2.9.0-beta.2","v2.9.0-beta.3","v2.9.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-30852.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P"}]}