Vulnerability-Lookup

ubuntu-cve-2026-4867

Vulnerability from osv_ubuntu

Published

2026-03-26 17:16

Modified

2026-04-02 17:29

Summary

Details

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.

Severity

7.5 (High)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-4867	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-4867	REPORT
	https://github.com/pillarjs/path-to-regexp/securi…	REPORT
	https://blakeembrey.com/posts/2024-09-web-redos	REPORT
	https://cna.openjsf.org/security-advisories.html	REPORT
	https://github.com/advisories/GHSA-9wv6-86v2-598j	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-path-to-regexp",
            "binary_version": "1.0.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "node-path-to-regexp",
        "purl": "pkg:deb/ubuntu/node-path-to-regexp@1.0.1-1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.0.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-path-to-regexp",
            "binary_version": "1.0.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "node-path-to-regexp",
        "purl": "pkg:deb/ubuntu/node-path-to-regexp@1.0.1-1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.0.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-path-to-regexp",
            "binary_version": "6.1.0-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "node-path-to-regexp",
        "purl": "pkg:deb/ubuntu/node-path-to-regexp@6.1.0-2?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.0.0-2",
        "3.1.0-1",
        "6.1.0-2"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2026-4867",
  "modified": "2026-04-02T17:29:41Z",
  "published": "2026-03-26T17:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-4867"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-4867"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-37ch-88jc-xwx2"
    },
    {
      "type": "REPORT",
      "url": "https://blakeembrey.com/posts/2024-09-web-redos"
    },
    {
      "type": "REPORT",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/advisories/GHSA-9wv6-86v2-598j"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-4867"
  ],
  "withdrawn": "2026-05-21T12:08:04Z"
}

CVE-2026-4867 (GCVE-0-2026-4867)

Vulnerability from cvelistv5 – Published: 2026-03-26 16:16 – Updated: 2026-03-26 16:52

Title

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

Summary

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-1333 - Inefficient Regular Expression Complexity

Assigner

openjs

References

3 references

URL	Tags
https://github.com/advisories/GHSA-9wv6-86v2-598j
https://blakeembrey.com/posts/2024-09-web-redos
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
path-to-regexp	path-to-regexp	Affected: 0 , < 0.1.13 (semver)

Credits

EthanKim88 blakeembrey UlisesGascon

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-4867",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-26T16:52:08.810671Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-26T16:52:14.893Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
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    "cna": {
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          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/path-to-regexp",
          "product": "path-to-regexp",
          "vendor": "path-to-regexp",
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      "credits": [
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          "lang": "en",
          "type": "reporter",
          "value": "EthanKim88"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "blakeembrey"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "UlisesGascon"
        }
      ],
      "descriptions": [
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          "lang": "en",
          "supportingMedia": [
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              "base64": false,
              "type": "text/html",
              "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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          "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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    "dateReserved": "2026-03-25T20:11:53.714Z",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

ubuntu-cve-2026-4867

Vulnerability from osv_ubuntu

CVE-2026-4867 (GCVE-0-2026-4867)

Tags

Sightings

Nomenclature