Is this true?

Hi List, I have my tmp directory on my / filesystem. Obviously executables are allowed for this filesystem. A friend of mine, though, claims that this can be a security problem because it helps attackers to run local exploits. From my point of view, it can do no more harm than an executable from an user's home directory. I am almost sure about that, but as I am not a guru I ask for further explanation. Is /tmp a danger if it can contains executables?? Note: I have to allow executables from users' home dir. Praise