Is CVE-2026-27588 actively exploited?

CVE-2026-27588 has no public evidence of in-the-wild exploitation as of 2026-02-25.

What is the CVSS score for CVE-2026-27588?

CVE-2026-27588 has a CVSS score of 7.7 (HIGH severity). Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X.

How do I patch CVE-2026-27588?

Patch guidance is available from caddyserver security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-27588.

Fix CVE-2026-27588 - HIGH caddyserver caddy

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.

CVSS Metrics

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector: network
Complexity: low
Privileges: none
User Action: none
Confidentiality: undefined
Integrity: undefined
Availability: undefined
Weaknesses: CWE-178

Metadata

Primary Vendor: CADDYSERVER
Published: 2/24/2026
Last Modified: 2/25/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

CVE-2026-27588

Description

CVSS Metrics

Metadata

Affected Products

Remediation Guidance

Executive Summary