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.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-m2w3-8f23-hxxf Caddy's vars_regexp double-expands user input, leaking env vars and files
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Sat, 07 Mar 2026 16:45:00 +0000

Type Values Removed Values Added
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.
Title Caddy: vars_regexp double-expands user input, leaking env vars and files
Weaknesses CWE-200
CWE-74
References
Metrics cvssV4_0

{'score': 5.5, 'vector': '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-07T16:28:26.894Z

Reserved: 2026-03-05T21:27:35.341Z

Link: CVE-2026-30852

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-07T17:15:52.733

Modified: 2026-03-07T17:15:52.733

Link: CVE-2026-30852

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses