CVE-2026-27588

CRITICAL
2026-02-24 [email protected] GHSA-x76f-jf84-rqj8
9.1
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

4
Patch Released
Mar 31, 2026 - 21:13 nvd
Patch available
Analysis Generated
Mar 12, 2026 - 21:55 vuln.today
PoC Detected
Feb 25, 2026 - 17:10 vuln.today
Public exploit code
CVE Published
Feb 24, 2026 - 17:29 nvd
CRITICAL 9.1

Tags

Tls Caddy Suse

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.

Analysis

Host header case sensitivity bypass in Caddy before 2.11.1. Virtual host routing can be bypassed by using alternate casing in the Host header. …

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Remediation

Within 24 hours: Inventory all Caddy deployments and identify instances with >100 host entries in configuration; implement emergency WAF rules to normalize request headers to lowercase. Within 7 days: Reduce host list entries below 100 where possible through consolidation or wildcard patterns; isolate affected Caddy instances from untrusted networks. …

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Priority Score

66
Low Medium High Critical
KEV: 0
EPSS: +0.0
CVSS: +46
POC: +20

Vendor Status

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CVE-2026-27588 vulnerability details – vuln.today
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