su vulnerability on coreutils 6.9 (64-bit Linux)

[Brian Biswas]

I have built the coreutils 6.9 package (the latest) on a 64-bit x86  
Linux system (Linux 2.6).

If as myself (not root) I type:

% su

I become root. No password asked!

Note: This software resides in AFS space. If I build it locally, the  
problem does not occur.

BTW, I've also built coreutils 6.9 on the following platforms (all out  
of AFS space):

        Solaris 9
        Solaris 10 (SPARC and x86)
        Mac OS X
        AIX 5.3
        Linux 2.4
        Linux 2.6 (32-bit)

None of them have this problem.