http-proxy-middleware `router` host+path substring matching allows Host-header-driven backend routing bypass_CVE-2026-55602

{
    "lastseen": "",
    "description": "http-proxy-middleware is node.js http-proxy middleware. From 0.16.0 until 2.0.10, 3.0.6, and 4.1.0, http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request metadata. As a result, a crafted Host header that is only a superstring match for a configured host+path key can still route a request to an unintended backend. This vulnerability is fixed in 2.0.10, 3.0.6, and 4.1.0.",
    "published": "2026-06-22T15:58:08.699Z",
    "modified": "2026-06-22T15:58:08.699Z",
    "type": "cve",
    "title": "http-proxy-middleware `router` host+path substring matching allows Host-header-driven backend routing bypass",
    "source": "GitHub_M",
    "references": "https://github.com/chimurai/http-proxy-middleware/security/advisories/GHSA-64mm-vxmg-q3vj",
    "id": "CVE-2026-55602",
    "bulletinFamily": "",
    "cwe": [
        "CWE-20",
        "CWE-187"
    ],
    "cvelist": null,
    "sourceData": "chimurai http-proxy-middleware >= 4.0.0, < 4.1.0\nchimurai http-proxy-middleware >= 3.0.0, < 3.0.6\nchimurai http-proxy-middleware >= 0.16.0, < 2.0.10",
    "sourceHref": "",
    "cvss": {
        "score": 6.9,
        "severity": "MEDIUM",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
        "version": "4.0"
    },
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        "baseScore": 0,
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        "privilegesRequired": "",
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        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
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    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "http-proxy-middleware",
    "version": ">= 4.0.0, < 4.1.0",
    "vendor": "chimurai",
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    "ai_score": 0
}