Use after free in PDFium in Google Chrome prior to 63.0.3239.84 allowed a remote attacker to potentially exploit heap corruption via a crafted PDF file.
https://www.debian.org/security/2017/dsa-4064
https://security.gentoo.org/glsa/201801-03
https://chromereleases.googleblog.com/2017/12/stable-channel-update-for-desktop.html