You're receiving this bug because the package in Summary has produced _FORTIFY_SOURCE related warnings indicating the presence of a sure overflow in a static buffer.
Even though this is not always an indication of a security problem it might even be. So please check this out ASAP.
By the way, _FORTIFY_SOURCE is disabled when you disable optimisation, so don't try finding out the cause using -O0.
Your friendly neighborhood tinderboxer
Created attachment 249936 [details]
Created attachment 250039 [details, diff]
Patch to ripmime-188.8.131.52.ebuild to address buffer overflow
This patch adds a sed call to rewrite the offending snprintf to use the correct length. Before applying it, you must also apply the ebuild patch posted in bug #334593 as attachment #244793 [details, diff] (which in turn applies new patch file attachment #244791 [details, diff]).
Fixed in CVS.