According to the announcement on oss-security:
imagemagick identify suffers of a global buffer overflow issue, which I
reported and has been patched, you can find a reproducer in the github bug
tracker issue link
Here is the patch for =media-gfx/imagemagick-18.104.22.168
>=media-gfx/imagemagick-22.214.171.124 have the patch included already.
Created attachment 449830 [details, diff]
patch for media-gfx/imagemagick-126.96.36.199
After further discussion with one of the package maintainers they intend to stabilize >=media-gfx/imagemagick-188.8.131.52
This issue was resolved and addressed in
GLSA 201611-21 at https://security.gentoo.org/glsa/201611-21
by GLSA coordinator Aaron Bauman (b-man).