There's a new version of modplugtools, 0.5.1, incorporating the patch I attached in bug 330897, fixing a buffer overflow. It would make sense to bump to this quickly, rather than patch 0.5.0.
+*modplugtools-0.5.1 (04 Aug 2010) + + 04 Aug 2010; Samuli Suominen <ssuominen@gentoo.org> + +modplugtools-0.5.1.ebuild: + Version bump wrt #331195 by Nick White.