Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS_CVE-2026-40487

{
    "lastseen": "",
    "description": "Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authenticated user to upload arbitrary HTML, SVG, or other executable file types to the server by spoofing the `Content-Type` header. The uploaded files are then served by nginx with a Content-Type derived from their original extension (`text/html`, `image/svg+xml`), enabling Stored Cross-Site Scripting (XSS) in the context of the application's origin. This can lead to session riding, account takeover, and full compromise of other users' accounts. Version 2.21.6 contains a fix.",
    "published": "2026-04-18T01:19:06.588Z",
    "modified": "2026-04-18T01:19:06.588Z",
    "type": "cve",
    "title": "Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS",
    "source": "GitHub_M",
    "references": "https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx\nhttps://github.com/gitroomhq/postiz-app/releases/tag/v2.21.6",
    "id": "CVE-2026-40487",
    "bulletinFamily": "",
    "cwe": [
        "CWE-79",
        "CWE-345",
        "CWE-434"
    ],
    "cvelist": null,
    "sourceData": "gitroomhq postiz-app < 2.21.6",
    "sourceHref": "",
    "cvss": {
        "score": 8.9,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L",
        "version": "3.1"
    },
    "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": "postiz-app",
    "version": "< 2.21.6",
    "vendor": "gitroomhq",
    "ai_description": "Stored Cross-Site Scripting (XSS) vulnerability due to file upload validation bypass via MIME type spoofing",
    "ai_severity": "High",
    "ai_vendor": "gitroomhq",
    "ai_product": "postiz-app",
    "ai_version": "< 2.21.6",
    "ai_score": 8.9
}