Vulnerability Details CVE-2026-27588
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 12.8%
CVSS Severity
CVSS v3 Score 9.1
References
Products affected by CVE-2026-27588
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cpe:2.3:a:caddyserver:caddy:2.10.2
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cpe:2.3:a:caddyserver:caddy:2.11.0