Apple today released a security update for iLife '08, called iLife Support 8.3.1. The update "improves overall stability and addresses a number of other minor issues," according to Apple. They recommend the update for all users of iLife '08 who are still using Tiger (up to Mac OS X 10.4.11). Leopard users are unaffected.
According to the Apple Knowledge Base, the update addresses three issues with ImageIO, a system component that allows applications to read and write popular image formats. Two of the issues were discovered by Apple, and concerned the way the component handled specially-created TIFF and JPEG images. Google found a third problem also related to meticulously-crafted TIFF images. All three issues, unpatched, could "lead to an unexpected application termination or arbitrary code execution."
The update can be downloaded via Software Update, or directly from Apple.