Permissions, Privileges, and Access Controls
The Node Access User Reference module 5.x before 5.x-2.0-beta4 and 6.x before 6.x-2.0-beta6, a module for Drupal, interprets an empty CCK user reference as a reference to the anonymous user, which might allow remote attackers to bypass intended access restrictions to read or modify a node.
CWE-264 - Permissions Privileges and Access Controls
CWE 264 (permissions, privileges, and access controls) is not a weakness in and of itself, rather it is a category of weaknesses related to the management of permissions, privileges, and other security features used to perform access control. If not addressed, the weaknesses in this category allow attackers to gain privileges for an unintended sphere of control, access sensitive information, and execute arbitrary commands.