# CVE-2020-7733: ua-parser-js regular expression denial of service

Source: https://junglewise.ai/threats/cve-2020-7733-ua-parser-js-regular-expression-denial-of-service  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-05-07. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2020-7733 · Severity: low · CVSS 3.1 · Published 2021-05-07

ua-parser-js is a popular JavaScript library used to parse user-agent strings from web browsers and mobile devices. A flaw in its regular expression matching logic can be exploited to cause the application to hang or consume excessive CPU resources when processing specially crafted user-agent strings, potentially disrupting service availability.

Technologies: [ua-parser-js (npm)](https://junglewise.ai/threats/technologies/ua-parser-js). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2020-7733 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2020-7733 being exploited in the wild.

**How severe is CVE-2020-7733?** Low severity, with a CVSS score of 3.1, published 7 May 2021.

**Which products and versions are affected?** ua-parser-js (npm) SEMVER:introduced=0,fixed=0.7.22.

**Is there a fix for CVE-2020-7733?** Yes. ua-parser-js (npm): upgrade to 0.7.22 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2020-7733 attacked?** It is attacked over the network.

**Am I affected by CVE-2020-7733?** Check whether you run ua-parser-js (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- ua-parser-js (npm): upgrade to 0.7.22 or later

  ```sh
  npm install ua-parser-js@0.7.22
  ```


## Technical details

This vulnerability is a Regular Expression Denial of Service (ReDoS) in ua-parser-js versions prior to 0.7.22. The root cause is a poorly constructed regular expression used to parse Redmi phones and Mi Pad tablets in user-agent strings, which exhibits catastrophic backtracking when processing certain input patterns. The vulnerability is network-accessible and requires no authentication or user interaction; an attacker can send malicious user-agent headers to trigger excessive regex evaluation. Successful exploitation causes denial of service by exhausting CPU resources. The fix was released in version 0.7.22 and is documented in commit 233d3ba.

## Affected products

- faisalman ua-parser-js before 0.7.22

## Identifiers

- CVE-2020-7733
- GHSA-662x-fhqg-9p8v

## Timeline

- 2021-05-07: disclosed: Advisory published
- 2020: patched: Fix available in version 0.7.22

## References

- [https://github.com/faisalman/ua-parser-js/commit/233d3bae22a795153a7e6638887ce159c63e557d](https://github.com/faisalman/ua-parser-js/commit/233d3bae22a795153a7e6638887ce159c63e557d)

## Related threats

- [faisalman UAParser.js ReDoS in withClientHints](https://junglewise.ai/threats/cve-2026-48125-faisalman-uaparser-js-redos-in-withclienthints)
- [ua-parser-js regular expression denial of service](https://junglewise.ai/threats/cve-2022-25927-ua-parser-js-regular-expression-denial-of-service)
- [ua-parser-js Regular Expression Denial of Service](https://junglewise.ai/threats/cve-2020-7793-ua-parser-js-regular-expression-denial-of-service)
- [ua-parser-js embedded malware in npm package](https://junglewise.ai/threats/cve-2021-4229-ua-parser-js-embedded-malware-in-npm-package)
- [ua-parser-js Regular Expression Denial of Service](https://junglewise.ai/threats/cve-2021-27292-ua-parser-js-regular-expression-denial-of-service)