Gotenberg SSRF via case-insensitive URL scheme bypass in webhook and downloadFrom deny-lists_CVE-2026-40280

{
    "lastseen": "",
    "description": "Gotenberg is an API-based document conversion tool. In versions 8.30.1 and earlier, the default private-IP deny-lists for the --webhook-deny-list and --api-download-from-deny-list flags use a case-sensitive regular expression (^https?://) to match URL schemes. Because Go's net/url.Parse() normalizes the scheme to lowercase before establishing the outbound TCP connection, an attacker can bypass the deny-list by simply capitalizing part of the URL scheme (e.g., HTTP://, HTTPS://, or Http://). This allows unauthenticated requests to reach internal network services, including private IP ranges, loopback addresses, and cloud instance metadata endpoints such as HTTP://169.254.169.254/latest/meta-data/. \n\nThis bypasses the same security control that was patched in CVE-2026-27018.\n\nThis issue has been fixed in version 8.31.0.",
    "published": "2026-05-05T19:52:40.327Z",
    "modified": "2026-05-05T19:52:40.327Z",
    "type": "cve",
    "title": "Gotenberg SSRF via case-insensitive URL scheme bypass in webhook and downloadFrom deny-lists",
    "source": "GitHub_M",
    "references": "https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5q7p-7jgv-ww56\nhttps://github.com/gotenberg/gotenberg/commit/3f01ca18d3cc21375a1e2da4b5a3f261c8548e47\nhttps://github.com/advisories/GHSA-jjwv-57xh-xr6r",
    "id": "CVE-2026-40280",
    "bulletinFamily": "",
    "cwe": [
        "CWE-918"
    ],
    "cvelist": null,
    "sourceData": "gotenberg gotenberg <= 8.30.1",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/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": "gotenberg",
    "version": "<= 8.30.1",
    "vendor": "gotenberg",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}