CVE-2026-27588 – Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass

CVE ID : CVE-2026-27588

Published : Feb. 24, 2026, 4:28 p.m. | 38 minutes ago

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.

Severity: 0.0 | NA

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