FOSSBilling: Authentication bypass allows unauthenticated administrator creation_CVE-2026-33543

{
    "lastseen": "",
    "description": "FOSSBilling is a free, open-source billing and client management system. Versions 0.7.2 and prior expose a guest API endpoint, /api/guest/staff/create, intended for initial administrator bootstrap. Due to a flawed admin-existence check, the endpoint remains usable after an administrator already exists. The flawed guard check uses is_countable() on a value that returns a Model_Admin object or null rather than a countable type, causing the expression to always evaluate as true and bypass the intended protection. As a result, an attacker can reach the unprotected endpoint to create a new administrator account and immediately authenticate, gaining a fully privileged admin session even when an admin already exists. This issue has been fixed in version 0.8.0.",
    "published": "2026-06-24T21:01:16.544Z",
    "modified": "2026-06-24T21:01:16.544Z",
    "type": "cve",
    "title": "FOSSBilling: Authentication bypass allows unauthenticated administrator creation",
    "source": "GitHub_M",
    "references": "https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-28mh-j262-q49w\nhttps://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0",
    "id": "CVE-2026-33543",
    "bulletinFamily": "",
    "cwe": [
        "CWE-288",
        "CWE-306"
    ],
    "cvelist": null,
    "sourceData": "FOSSBilling FOSSBilling < 0.8.0",
    "sourceHref": "",
    "cvss": {
        "score": 9.3,
        "severity": "CRITICAL",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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": "FOSSBilling",
    "version": "< 0.8.0",
    "vendor": "FOSSBilling",
    "ai_description": "Authentication bypass vulnerability in FOSSBilling allows unauthenticated administrator creation",
    "ai_severity": "Critical",
    "ai_vendor": "FOSSBilling",
    "ai_product": "FOSSBilling",
    "ai_version": "0.7.2 and prior",
    "ai_score": 9.3
}