The SP Project & Document Manager WordPress plugin before 4.22 allows users to upload files, however, the plugin attempts to prevent php and other similar files that could be executed on the server from being uploaded by checking the file extension. It was discovered that php files could still be uploaded by changing the file extension's case, for example, from "php" to "pHP".

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-24347
• https://wpscan.com/vulnerability/8f6e82d5-c0e9-468e-acb8-7cd549f6a45a
• http://packetstormsecurity.com/files/163434/WordPress-SP-Project-And-Document-Manager-4.21-Shell-Upload.html
• http://packetstormsecurity.com/files/163675/WordPress-SP-Project-And-Document-Remote-Code-Execution.html