The file manager option in CuppaCMS before 2019-11-12 allows an authenticated attacker to upload a malicious file within an image extension and through a custom request using the rename function provided by the file manager is able to modify the image extension into PHP resulting in remote arbitrary code execution.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26048
Reference (s):
- https://github.com/CuppaCMS/CuppaCMS/issues/7