path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters_CVE-2026-4867

{
    "lastseen": "",
    "description": "Impact:\n\nA bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in [email protected] only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.\n\nPatches:\n\nUpgrade to [email protected]\n\nCustom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.\n\nWorkarounds:\n\nAll versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).\n\nIf paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.",
    "published": "2026-03-26T16:16:25.501Z",
    "modified": "2026-03-26T16:52:14.893Z",
    "type": "cve",
    "title": "path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters",
    "source": "openjs",
    "references": "https://github.com/advisories/GHSA-9wv6-86v2-598j\nhttps://blakeembrey.com/posts/2024-09-web-redos\nhttps://cna.openjsf.org/security-advisories.html",
    "id": "CVE-2026-4867",
    "bulletinFamily": "",
    "cwe": [
        "CWE-1333"
    ],
    "cvelist": null,
    "sourceData": "path-to-regexp path-to-regexp 0",
    "sourceHref": "",
    "cvss": {
        "score": 7.5,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
        "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": "",
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            "confidentialityImpact": "",
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            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "path-to-regexp",
    "version": "0",
    "vendor": "path-to-regexp",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}