http-proxy-middleware: multipart/form-data field injection via unescaped CRLF in `fixRequestBody`_CVE-2026-55603

{
    "lastseen": "",
    "description": "http-proxy-middleware is node.js http-proxy middleware. From 3.0.4 until 3.0.7 and 4.1.1, fixRequestBody() is the library's documented helper for re-emitting a request body that was already consumed by a body parser. When the outgoing Content-Type is multipart/form-data, it rebuilds the body with handlerFormDataBodyData(), which interpolates each req.body key and value directly into the multipart wire format without neutralizing CR/LF. A \\r\\n inside a value (or key) lets an attacker close the current part and inject an entirely new form part. Because the proxy's own body parser saw a single opaque value, any gateway-side policy or validation performed on req.body is evaluated against a different set of fields than the upstream backend ultimately parses a request/parameter desynchronization across the trust boundary. This vulnerability is fixed in 3.0.7 and 4.1.1.",
    "published": "2026-06-22T20:07:05.034Z",
    "modified": "2026-06-22T20:07:05.034Z",
    "type": "cve",
    "title": "http-proxy-middleware: multipart/form-data field injection via unescaped CRLF in `fixRequestBody`",
    "source": "GitHub_M",
    "references": "https://github.com/chimurai/http-proxy-middleware/security/advisories/GHSA-gcq2-9pq2-cxqm",
    "id": "CVE-2026-55603",
    "bulletinFamily": "",
    "cwe": [
        "CWE-93"
    ],
    "cvelist": null,
    "sourceData": "chimurai http-proxy-middleware >= 3.0.4, < 3.0.7\nchimurai http-proxy-middleware >= 4.0.0, < 4.1.1",
    "sourceHref": "",
    "cvss": {
        "score": 7.5,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/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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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "http-proxy-middleware",
    "version": ">= 3.0.4, < 3.0.7",
    "vendor": "chimurai",
    "ai_description": "",
    "ai_severity": "",
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    "ai_score": 0
}