Evince is a document viewer for multiple document formats, including PostScript.
Evince includes code from GNU gv that does not properly boundary check user-supplied data before copying it into process buffers.
An attacker could entice a user to open a specially crafted PostScript document with Evince and possibly execute arbitrary code with the rights of the user running Evince.
There is no known workaround at this time.
All Evince users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-text/evince-0.6.1-r3"