A use-after-free vulnerability can occur when arguments passed to the "IsPotentiallyScrollable" function are freed while still in use by scripts. This results in a potentially exploitable crash. This vulnerability affects Firefox < 58.
https://www.mozilla.org/security/advisories/mfsa2018-02/
https://usn.ubuntu.com/3544-1/
https://bugzilla.mozilla.org/show_bug.cgi?id=1417405