Pixman is a pixel manipulation library.
The trapezoid handling code in Pixman contains an integer underflow vulnerability.
A context-dependent attacker could entice a user to open a specially crafted file using an application linked against Pixman, possibly resulting in execution of arbitrary code with the privileges of the process, or a Denial of Service condition.
There is no known workaround at this time.
All Pixman users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=x11-libs/pixman-0.32.4"
Packages which depend on this library may need to be recompiled. Tools such as revdep-rebuild may assist in identifying these packages.