FKIE_CVE-2026-4867

Vulnerability from fkie_nvd - Published: 2026-03-26 17:16 - Updated: 2026-04-16 18:01
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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.
References
ce714d77-add3-4f53-aff5-83d477b104bbhttps://blakeembrey.com/posts/2024-09-web-redosTechnical Description
ce714d77-add3-4f53-aff5-83d477b104bbhttps://cna.openjsf.org/security-advisories.htmlThird Party Advisory
ce714d77-add3-4f53-aff5-83d477b104bbhttps://github.com/advisories/GHSA-9wv6-86v2-598jNot Applicable
Impacted products
Vendor Product Version
pillarjs path-to-regexp *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:pillarjs:path-to-regexp:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "AD9DFD27-4A53-4409-9DAC-8E326EBB3303",
              "versionEndExcluding": "0.1.13",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "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."
    },
    {
      "lang": "es",
      "value": "Impacto:\n\nSe genera una expresi\u00f3n regular incorrecta cada vez que se tienen tres o m\u00e1s par\u00e1metros dentro de un \u00fanico segmento, separados por algo que no sea un punto (.). Por ejemplo, /:a-:b-:c o /:a-:b-:c-:d. La protecci\u00f3n contra retroceso a\u00f1adida en path-to-regexp@0.1.12 solo previene la ambig\u00fcedad para dos par\u00e1metros. Con tres o m\u00e1s, el \u0027lookahead\u0027 generado no bloquea los caracteres separadores individuales, por lo que los grupos de captura se superponen y causan un retroceso catastr\u00f3fico.\n\nParches:\n\nActualizar a path-to-regexp@0.1.13\n\nLos patrones de expresiones regulares personalizados en las definiciones de ruta (por ejemplo, /:a-:b([^-/]+)-:c([^-/]+)) no se ven afectados porque anulan el grupo de captura predeterminado.\n\nSoluciones provisionales:\n\nTodas las versiones pueden ser parcheadas proporcionando una expresi\u00f3n regular personalizada para los par\u00e1metros despu\u00e9s del primero en un \u00fanico segmento. Siempre y cuando la expresi\u00f3n regular personalizada no coincida con el texto anterior al par\u00e1metro, estar\u00e1 seguro. Por ejemplo, cambie /:a-:b-:c a /:a-:b([^-/]+)-:c([^-/]+).\n\nSi las rutas no pueden ser reescritas y las versiones no pueden ser actualizadas, otra alternativa es limitar la longitud de la URL."
    }
  ],
  "id": "CVE-2026-4867",
  "lastModified": "2026-04-16T18:01:04.783",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-03-26T17:16:42.983",
  "references": [
    {
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "tags": [
        "Technical Description"
      ],
      "url": "https://blakeembrey.com/posts/2024-09-web-redos"
    },
    {
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "tags": [
        "Not Applicable"
      ],
      "url": "https://github.com/advisories/GHSA-9wv6-86v2-598j"
    }
  ],
  "sourceIdentifier": "ce714d77-add3-4f53-aff5-83d477b104bb",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1333"
        }
      ],
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "type": "Secondary"
    }
  ]
}


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