Dillo is a small and fast multi-platform web browser based on GTK+.
Gentoo Linux developer Tavis Ormandy found a format string bug in Dillo's handling of messages in a_Interface_msg().
An attacker could craft a malicious web page which, when accessed using Dillo, would trigger the format string vulnerability and potentially execute arbitrary code with the rights of the user running Dillo.
There is no known workaround at this time.
All Dillo users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-client/dillo-0.8.3-r4"