The rand and mt_rand functions in PHP < 5.4.x do not produce cryptographically strong random numbers, which allows attackers to leverage exposures in products that rely on these functions for security-relevant functionality, as demonstrated by the password-reset functionality in ownCloud 4.0.x.
It is recommended that all instances are upgraded to ownCloud Server 4.0.8.
The ownCloud team thanks the following people for their research and responsible disclosure of the above advisory: