Provide references for CVE-2021-4240.
Where can I find more information about CVE-2021-4240?
References are available at: https://huntr.dev/bounties/2-phpservermon/phpservermon/, https://github.com/phpservermon/phpservermon/commit/3daa804d5f56c55b3ae13bfac368bb84ec632193, https://vuldb.com/?id.213717.