CVEs-PoC/2021/CVE-2021-22901.md

### [CVE-2021-22901](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-22901)
![](https://img.shields.io/static/v1?label=Product&message=https%3A%2F%2Fgithub.com%2Fcurl%2Fcurl&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=Use%20After%20Free%20(CWE-416)&color=brighgreen)

### Description

curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session ticket arrives over a connection. A malicious server can use this in rare unfortunate circumstances to potentially reach remote code execution in the client. When libcurl at run-time sets up support for TLS 1.3 session tickets on a connection using OpenSSL, it stores pointers to the transfer in-memory object for later retrieval when a session ticket arrives. If the connection is used by multiple transfers (like with a reused HTTP/1.1 connection or multiplexed HTTP/2 connection) that first transfer object might be freed before the new session is established on that connection and then the function will access a memory buffer that might be freed. When using that memory, libcurl might even call a function pointer in the object, making it possible for a remote code execution if the server could somehow manage to get crafted memory content into the correct place in memory.

### POC

#### Reference
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html

#### Github
- https://github.com/ARPSyndicate/cvemon
- https://github.com/chnzzh/OpenSSL-CVE-lib
- https://github.com/falk-werner/cve-check