Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass
Summary
Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass
Original description
The description as published by the source.
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.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-27588 caddy
- Ubuntu UBUNTU-CVE-2026-27588 caddy
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- web github.com