A denial of service flaw (infinite loop) was found in the way ImageMagick processed certain PDB files:
Upstream issue, including a reproducer:
A patch is not yet available as noted in comment 2 of the above-linked issue.
Created ImageMagick tracking bugs for this issue:
Affects: fedora-all [bug 1195270]
A patch for this issue in IM6 should be available here: http://trac.imagemagick.org/changeset/17855
ImageMagick-188.8.131.52-9.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.