Authentication bypass vulnerability in GitHub Enterprise Server allowed creation of local user accounts bypassing the configured external identity provider_CVE-2026-6736

{
    "lastseen": "",
    "description": "An authentication bypass vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to create a local user account, bypassing the configured external identity provider. When external authentication was enabled, the signup endpoint did not properly enforce the authentication restriction, allowing account creation and session establishment without identity provider validation. The created account was limited to the default base permissions configured on the instance. Exploitation required network access to a GHES instance configured with an external authentication provider. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.2, 3.19.6, 3.18.9, 3.17.15, and 3.16.18.",
    "published": "2026-05-07T21:14:33.490Z",
    "modified": "2026-05-07T21:27:45.553Z",
    "type": "cve",
    "title": "Authentication bypass vulnerability in GitHub Enterprise Server allowed creation of local user accounts bypassing the configured external identity provider",
    "source": "GitHub_P",
    "references": "https://docs.github.com/en/[email protected]/admin/release-notes#3.16.18\nhttps://docs.github.com/en/[email protected]/admin/release-notes#3.17.15\nhttps://docs.github.com/en/[email protected]/admin/release-notes#3.18.9\nhttps://docs.github.com/en/[email protected]/admin/release-notes#3.19.6\nhttps://docs.github.com/en/[email protected]/admin/release-notes#3.20.2",
    "id": "CVE-2026-6736",
    "bulletinFamily": "",
    "cwe": [
        "CWE-306"
    ],
    "cvelist": null,
    "sourceData": "GitHub Enterprise Server 3.16.0\nGitHub Enterprise Server 3.17.0\nGitHub Enterprise Server 3.18.0\nGitHub Enterprise Server 3.19.0\nGitHub Enterprise Server 3.20.0",
    "sourceHref": "",
    "cvss": {
        "score": 6.3,
        "severity": "MEDIUM",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Enterprise Server",
    "version": "3.16.0",
    "vendor": "GitHub",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}