Sudo Private File Existance Information Leakage Vulnerability
A vulnerability in Sudo allows local malicious users to determine whether specific files under unreadable directories exist.
Sudo is a utility that allows the execution of preconfigured commands as root by authorized users after being authenticated. When sudo is executed with a filename as an argument of a file that exists under a directory non-readable by the user the error message is "<user> is not in the sudoers file. This incident will be reported.". if the file does not exists under the non-readable directory by the user the error is "sudo: <the filename>: No such file or directory". This allow a local malicious user if the filename exists or not.
This is the result of sudo checking for the file existance as root before it checks the sudoers list of people allowed to execute sudo.
This is Debian BugID 39255.