The Spellcheck API implementation in Google Chrome before 43.0.2357.65 does not use an HTTPS session for downloading a Hunspell dictionary, which allows man-in-the-middle attackers to deliver incorrect spelling suggestions or possibly have unspecified other impact via a crafted file.
https://security.gentoo.org/glsa/201506-04
https://codereview.chromium.org/1056103005
https://code.google.com/p/chromium/issues/detail?id=479162
http://www.securitytracker.com/id/1032375
http://www.securityfocus.com/bid/74723
http://www.debian.org/security/2015/dsa-3267
http://lists.opensuse.org/opensuse-updates/2015-11/msg00015.html
http://lists.opensuse.org/opensuse-updates/2015-05/msg00091.html
http://googlechromereleases.blogspot.com/2015/05/stable-channel-update_19.html