CVEs-PoC/2021/CVE-2021-21317.md

### [CVE-2021-21317](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21317)
![](https://img.shields.io/static/v1?label=Product&message=uap-core&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-400%3A%20Uncontrolled%20Resource%20Consumption&color=brighgreen)

### Description

uap-core in an open-source npm package which contains the core of BrowserScope's original user agent string parser. In uap-core before version 0.11.0, some regexes are vulnerable to regular expression denial of service (REDoS) due to overlapping capture groups. This allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to maliciously crafted long strings. This is fixed in version 0.11.0. Downstream packages such as uap-python, uap-ruby etc which depend upon uap-core follow different version schemes.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/engn33r/awesome-redos-security
- https://github.com/yetingli/PoCs