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.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/caddyserver/caddy/releases/tag/v2.11.1	Release Notes
https://github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*

History

25 Feb 2026, 17:10

Type	Values Removed	Values Added
CPE		cpe:2.3:a:caddyserver:caddy::::::::
References	~~() https://github.com/caddyserver/caddy/releases/tag/v2.11.1 -~~	() https://github.com/caddyserver/caddy/releases/tag/v2.11.1 - Release Notes
References	~~() https://github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8 -~~	() https://github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8 - Exploit, Vendor Advisory
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.1
First Time		Caddyserver Caddyserver caddy

24 Feb 2026, 17:29

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-02-24 17:29

Updated : 2026-02-25 17:10

NVD link : CVE-2026-27588

Mitre link : CVE-2026-27588

CVE.ORG link : CVE-2026-27588

JSON object : View

Products Affected

caddyserver

caddy

CWE

CWE-178

Improper Handling of Case Sensitivity

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