Medium 5.5Published Mar 7, 2026

CVE-2026-30852Caddy: vars_regexp double-expands user input, leaking env vars and files

Updated under an hour ago (Oct 26, 2026, 2:23 PM ET)

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It affects caddyserver caddy. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for caddyserver caddy

Exploited in the last 30 days

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.

CVSS: 5.5 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-200, CWE-74
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Mar 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

caddyserver caddy caddyserver:caddy (from the name)	from 2.7.5, < 2.11.2	CNA record
caddyserver caddy caddyserver:caddy	from 2.7.5 before 2.11.2	NVD

References

References

https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxf	x-refsource-confirm, exploit, mitigation, vendor-advisory
https://github.com/caddyserver/caddy/pull/5408	x-refsource-misc, issue-tracking, patch
https://github.com/caddyserver/caddy/releases/tag/v2.11.2	x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.