Security bug in SLES 11 & 12 for VNC


I have found a security bug in SLES 11 & 12 any SP version.

Bug : If my vncserver password is more than eight characters then it is also possible to connect using eight characters and after them anything.

Lets say VNC my password is “P@ssword123” then i can also connect with typing “P@ssword” or “P@ssword654 or (any character)”.

Anyone noticed it?

Please suggest to resolve this issue.


Hi, this is not a support forum for generic problems. Please use the support means included in your SUSE Linux Enterprise Linux subscription.

Hi raheelqaiser2,

This is an old and known bug.

Most VNC systems implements their authentication using DES encryption (
You can read more about the details on the Wikipedia link, but in short, DES limits key sizes to 8 bytes (characters). Passwords shorter than 8 are padded with zeroes.

Some implementations allows passwords to be longer than 8 (RealVNC allows 255 for example). But then, if you connect to a server that is using the standard authentication implementation, your password will just be silently be trimmed to 8 characters, ignoring anything beyond that.

Hope this helps.