Rack: Rack::Sendfile regex injection via HTTP_X_ACCEL_MAPPING header allows arbitrary file reads through nginx_CVE-2026-34830

{
    "lastseen": "",
    "description": "Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Sendfile#map_accel_path interpolates the value of the X-Accel-Mapping request header directly into a regular expression when rewriting file paths for X-Accel-Redirect. Because the header value is not escaped, an attacker who can supply X-Accel-Mapping to the backend can inject regex metacharacters and control the generated X-Accel-Redirect response header. In deployments using Rack::Sendfile with x-accel-redirect, this can allow an attacker to cause nginx to serve unintended files from configured internal locations. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.",
    "published": "2026-04-02T16:47:40.490Z",
    "modified": "2026-04-02T18:59:46.589Z",
    "type": "cve",
    "title": "Rack: Rack::Sendfile regex injection via HTTP_X_ACCEL_MAPPING header allows arbitrary file reads through nginx",
    "source": "GitHub_M",
    "references": "https://github.com/rack/rack/security/advisories/GHSA-qv7j-4883-hwh7",
    "id": "CVE-2026-34830",
    "bulletinFamily": "",
    "cwe": [
        "CWE-625"
    ],
    "cvelist": null,
    "sourceData": "rack rack < 2.2.23\nrack rack >= 3.0.0.beta1, < 3.1.21\nrack rack >= 3.2.0, < 3.2.6",
    "sourceHref": "",
    "cvss": {
        "score": 5.9,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
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        "baseScore": 0,
        "baseSeverity": "",
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        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
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            "baseScore": 0,
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            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "rack",
    "version": "< 2.2.23",
    "vendor": "rack",
    "ai_description": "",
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    "ai_score": 0
}