Pngcrush is a multi platform optimizer for PNG (Portable Network Graphics) files.
It has been reported that Pngcrush includes a copy of libpng that is vulnerable to a memory corruption (GLSA 200804-15).
A remote attacker could entice a user to process a specially crafted PNG image, possibly resulting in the execution of arbitrary code with the privileges of the user running the application, or a Denial of Service.
There is no known workaround at this time.
All Pngcrush users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=media-gfx/pngcrush-1.6.4-r1"