CVE-2026-27588

9.1 CRITICAL
Published: February 24, 2026 Modified: February 25, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/caddyserver/caddy/releases/tag/v2.11.1
Source: security-advisories@github.com
Release Notes
https://github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8
Source: security-advisories@github.com
Exploit Vendor Advisory

2 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.1 / 10.0
EPSS (Exploit Probability)
0.0%
12th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

caddyserver