CVE-2026-30852
Last modified
CVE-2026-30852 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. 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. EPSS estimates a 0.40% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Caddyserver | Caddy | >= 2.7.5, < 2.11.2 |
References
- https://github.com/caddyserver/caddy/pull/5408Issue Tracking, Patch
- https://github.com/caddyserver/caddy/releases/tag/v2.11.2Product, Release Notes
- https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxfExploit, Mitigation, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-30852?
How severe is CVE-2026-30852?
How do I fix CVE-2026-30852?
Are you affected by CVE-2026-30852?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST