CVEs-PoC/2021/CVE-2021-25831.md

### [CVE-2021-25831](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-25831)
![](https://img.shields.io/static/v1?label=Product&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa%20&color=brightgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=n%2Fa&color=brightgreen)

### Description

A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer v4.0.0-9-v5.6.3. An attacker must request the conversion of the crafted file from PPTT into PPTX format. Using the chain of two other bugs related to improper string handling, a remote attacker can obtain remote code execution on DocumentServer.

### POC

#### Reference
- https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25831

#### Github
- https://github.com/konatabrk/POC-onlyoffice
- https://github.com/merrychap/POC-onlyoffice