yelp is the default help browser for GNOME.
Aaron Grattafiori reported a format string vulnerability in the window_error() function in yelp-window.c.
A remote attacker can entice a user to open specially crafted "man:" or "ghelp:" URIs in yelp, or an application using yelp such as Firefox or Evolution, and execute arbitrary code with the privileges of that user.
There is no known workaround at this time.
All yelp users running GNOME 2.22 should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=gnome-extra/yelp-2.22.1-r2"
All yelp users running GNOME 2.20 should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=gnome-extra/yelp-2.20.0-r1"