CVE-2026-27588
Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass
- State
- Published
- Severity
- 7.7 High
- Published
- Feb 24, 2026
- Updated
- Feb 27, 2026
- Reserved
- Feb 20, 2026
Description
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's HTTP `host` request matcher is documented as case-insensitive, but when configured with a large host list (>100 entries) it becomes case-sensitive due to an optimized matching path. An attacker can bypass host-based routing and any access controls attached to that route by changing the casing of the `Host` header. Version 2.11.1 contains a fix for the issue.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.7 High | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P | GitHub_M |
Weaknesses
- CWE-178 Improper Handling of Case Sensitivity
Affected Products
| Product | Versions |
|---|---|
caddycaddyserver |
|
References
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