path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters

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  "cveMetadata": {
    "cveId": "CVE-2026-4867",
    "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
    "assignerShortName": "openjs",
    "dateUpdated": "2026-03-26T16:52:14.893Z",
    "dateReserved": "2026-03-25T20:11:53.714Z",
    "datePublished": "2026-03-26T16:16:25.501Z",
    "state": "PUBLISHED"
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        "dateUpdated": "2026-03-26T16:16:25.501Z"
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      "title": "path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters",
      "descriptions": [
        {
          "lang": "en",
          "value": "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 path-to-regexp@0.1.12 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 path-to-regexp@0.1.13\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.",
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              "value": "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 path-to-regexp@0.1.12 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 path-to-regexp@0.1.13\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."
            }
          ]
        }
      ],
      "affected": [
        {
          "vendor": "path-to-regexp",
          "product": "path-to-regexp",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "0.1.13"
            }
          ]
        }
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      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-1333: Inefficient Regular Expression Complexity",
              "cweId": "CWE-1333",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/advisories/GHSA-9wv6-86v2-598j"
        },
        {
          "url": "https://blakeembrey.com/posts/2024-09-web-redos"
        },
        {
          "url": "https://cna.openjsf.org/security-advisories.html"
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            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "baseScore": 7.5,
            "baseSeverity": "HIGH"
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        {
          "lang": "en",
          "value": "EthanKim88",
          "type": "reporter"
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