NAS4Free 9.1.0.1.804 and earlier allows remote authenticated users to execute arbitrary PHP code via a request to exec.php, aka the "Advanced | Execute Command" feature. NOTE: this issue might not be a vulnerability, since it appears to be part of legitimate, intentionally-exposed functionality by the developer and is allowed within the intended security policy.

References

• https://nvd.nist.gov/vuln/detail/CVE-2013-3631
• https://community.rapid7.com/community/metasploit/blog/2013/10/30/seven-tricks-and-treats
• http://www.kb.cert.org/vuls/id/326830