cve/2021/CVE-2021-21708.md

### [CVE-2021-21708](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21708)
![](https://img.shields.io/static/v1?label=Product&message=PHP&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=7.4.x%3C%207.4.28%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-416%20Use%20After%20Free&color=brighgreen)

### Description

In PHP versions 7.4.x below 7.4.28, 8.0.x below 8.0.16, and 8.1.x below 8.1.3, when using filter functions with FILTER_VALIDATE_FLOAT filter and min/max limits, if the filter fails, there is a possibility to trigger use of allocated memory after free, which can result it crashes, and potentially in overwrite of other memory chunks and RCE. This issue affects: code that uses FILTER_VALIDATE_FLOAT with min/max limits.

### POC

#### Reference
- https://bugs.php.net/bug.php?id=81708

#### Github
- https://github.com/ARPSyndicate/cvemon
- https://github.com/Sergio-F20/GPT-FastPentest