CVE-2026-27588

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.

PUBLISHED Reserved 2026-02-20 | Published 2026-02-24 | Updated 2026-02-24 | Assigner GitHub_M

Problem types

CWE-178: Improper Handling of Case Sensitivity

Product status

References

github.com/.../caddy/security/advisories/GHSA-x76f-jf84-rqj8

github.com/caddyserver/caddy/releases/tag/v2.11.1

cve.org (CVE-2026-27588)

nvd.nist.gov (CVE-2026-27588)

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