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

{
  "id": "1cb7c0637281ce4a7114d1cb43b53b9e3b9e428ff12db172f5cabb7fdba6983f",
  "url": "https://osv.dev/vulnerability/CVE-2026-4867",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters",
    "summary": "Impact: A 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. Patches: Upgrade to path-to-regexp@0.1.13 Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group. Workarounds: All 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([^-/]+). If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.",
    "evidence": "osv:CVE-2026-4867",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-4867",
      "aliases": [
        "CVE-2024-45296",
        "CVE-2026-4867",
        "GHSA-37ch-88jc-xwx2",
        "GHSA-9wv6-86v2-598j"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/pillarjs/path-to-regexp",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "9fd0c879f232c2464591f56dd7c7edad7f45b4e0"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:pillarjs:path-to-regexp:*:*:*:*:*:node.js:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.1.13"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.1.12",
            "v0.1.11",
            "v0.1.10",
            "v0.1.9",
            "v0.1.8",
            "v0.1.7",
            "v0.1.6",
            "v0.1.5",
            "v0.1.4",
            "v0.1.3",
            "v0.1.2",
            "v0.1.1",
            "0.1.0",
            "0.0.2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-4867.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:52.349197254Z",
      "provider": "osv",
      "references": [
        "https://blakeembrey.com/posts/2024-09-web-redos",
        "https://cna.openjsf.org/security-advisories.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4867.json",
        "https://github.com/advisories/GHSA-9wv6-86v2-598j",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-4867"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1333"
        ],
        "cna_assigner": "openjs",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "fixed": "0.1.13"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          }
        ],
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4867.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-45296",
        "evidence": "/aliases"
      },
      {
        "value": "CVE-2026-4867",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 521347,
  "published_at": "2026-03-26T16:16:25.501+00:00"
}