CVE-2026-27588

CRITICAL

9.1

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.

CVE Details

CVSS v3.1 Score9.1

SeverityCRITICAL

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published2/24/2026

Last Modified2/25/2026

Sourcenvd

Honeypot Sightings0

Affected Products

caddyserver:caddy

Weaknesses (CWE)

CWE-178

References

https://github.com/caddyserver/caddy/releases/tag/v2.11.1(security-advisories@github.com)

https://github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8(security-advisories@github.com)

IOC Correlations

No correlations recorded

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