cve/2021/CVE-2021-28957.md

### [CVE-2021-28957](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-28957)
![](https://img.shields.io/static/v1?label=Product&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=n%2Fa&color=brighgreen)

### Description

An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3.

### POC

#### Reference
- https://www.oracle.com/security-alerts/cpuoct2021.html

#### Github
No PoCs found on GitHub currently.