{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-27586",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-02-20T17:40:28.450Z",
        "datePublished": "2026-02-24T16:08:20.569Z",
        "dateUpdated": "2026-02-26T20:56:20.526Z"
    },
    "containers": {
        "cna": {
            "title": "Caddy's mTLS client authentication silently fails open when CA certificate file is missing or malformed",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-755",
                            "lang": "en",
                            "description": "CWE-755: Improper Handling of Exceptional Conditions",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "vulnIntegrityImpact": "HIGH",
                        "vulnAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "baseScore": 8.8,
                        "baseSeverity": "HIGH",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P",
                        "version": "4.0"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7"
                },
                {
                    "name": "https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48"
                },
                {
                    "name": "https://github.com/caddyserver/caddy/releases/tag/v2.11.1",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/caddyserver/caddy/releases/tag/v2.11.1"
                }
            ],
            "affected": [
                {
                    "vendor": "caddyserver",
                    "product": "caddy",
                    "versions": [
                        {
                            "version": "< 2.11.1",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-02-24T16:08:20.569Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in `ClientAuthentication.provision()` cause mTLS client certificate authentication to silently fail open when a CA certificate file is missing, unreadable, or malformed. The server starts without error but accepts any client certificate signed by any system-trusted CA, completely bypassing the intended private CA trust boundary. Any deployment using `trusted_ca_cert_file` or `trusted_ca_certs_pem_files` for mTLS will silently degrade to accepting any system-trusted client certificate if the CA file becomes unavailable. This can happen due to a typo in the path, file rotation, corruption, or permission changes. The server gives no indication that mTLS is misconfigured. Version 2.11.1 fixes the vulnerability."
                }
            ],
            "source": {
                "advisory": "GHSA-hffm-g8v7-wrv7",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-02-26T20:55:27.670740Z",
                                "id": "CVE-2026-27586",
                                "options": [
                                    {
                                        "Exploitation": "poc"
                                    },
                                    {
                                        "Automatable": "yes"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-02-26T20:56:20.526Z"
                }
            }
        ]
    }
}