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CVE PROGRAM SOURCE RECORD7.7 High

CVE-2026-27588

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

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

caddyserver caddy

  • < 2.11.1affected

References