CUPS provides a portable printing layer for UNIX-based operating systems.
Thomas Pollet reported a possible integer overflow vulnerability in the PNG image handling in the file filter/image-png.c.
A malicious user might be able to execute arbitrary code with the privileges of the user running CUPS (usually lp), or cause a Denial of Service by sending a specially crafted PNG image to the print server. The vulnerability is exploitable via the network if CUPS is sharing printers remotely.
There is no known workaround at this time.
All CUPS users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-print/cups-1.2.12-r8"