Discuz! X5.0 Authentication Bypass via dbbak.php Encryption Oracle_CVE-2026-49952

{
    "lastseen": "",
    "description": "Discuz! X5.0 releases 20260320 through 20260501 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to gain unauthorized access to database backup and restore functionality by exploiting a shared cryptographic key between UCenter integration and the database backup API exposed by dbbak.php. Attackers can inject a crafted payload through the username parameter during login to abuse the encryption oracle in logging_ctl::logging_more(), obtain a legitimately signed token, and use it to bypass authorization for database export and import operations, with the additional ability to trigger a race condition to impersonate arbitrary users.",
    "published": "2026-06-15T18:43:21.990Z",
    "modified": "2026-06-15T18:52:07.338Z",
    "type": "cve",
    "title": "Discuz! X5.0 Authentication Bypass via dbbak.php Encryption Oracle",
    "source": "VulnCheck",
    "references": "https://karmainsecurity.com/KIS-2026-09\nhttps://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce\nhttps://gitee.com/Discuz/DiscuzX/commit/9962dad52c4c6999dabaf91ecd70377c680ff3c6\nhttps://www.vulncheck.com/advisories/discuz-x5-0-authentication-bypass-via-dbbak-php-encryption-oracle",
    "id": "CVE-2026-49952",
    "bulletinFamily": "",
    "cwe": [
        "CWE-323"
    ],
    "cvelist": null,
    "sourceData": "Discuz! Discuz! X5.0 20260320",
    "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: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": "Discuz! X5.0",
    "version": "20260320",
    "vendor": "Discuz!",
    "ai_description": "Authentication bypass vulnerability allowing unauthorized access to database backup and restore functionality",
    "ai_severity": "Critical",
    "ai_vendor": "Comsenz",
    "ai_product": "Discuz! X5.0",
    "ai_version": "20260320",
    "ai_score": 9.3
}