CVE-2026-27588

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Source
https://cve.org/CVERecord?id=CVE-2026-27588
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27588.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-27588
Aliases
Downstream
Related
Published
2026-02-24T16:28:28.106Z
Modified
2026-07-31T18:30:51.623946229Z
Severity
  • 7.7 (High) CVSS_V4 - 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 CVSS Calculator
Summary
Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass
Details

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.

Database specific 
{
    "cwe_ids": [
        "CWE-178"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27588.json",
    "cna_assigner": "GitHub_M"
}
References

Affected packages

Git / github.com/caddyserver/caddy

Affected ranges

Type
GIT
Repo
https://github.com/caddyserver/caddy
Events
Introduced
551f793700fe1550845c824470b623fd1aa03d36
Fixed
6610e2f1bd8f54853006eefd3849c9965190e57f
Database specific 
{
    "cpe": "cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*",
    "source": [
        "AFFECTED_FIELD",
        "CPE_RANGE",
        "REFERENCES"
    ],
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "2.11.1"
        },
        {
            "introduced": "2.10.2"
        }
    ]
}

Affected versions

v2.*
v2.10.2
v2.11.0
v2.11.0-beta.1
v2.11.0-beta.2

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27588.json"