Mozilla Firefox before 48.0 and Firefox ESR 45.x before 45.3 process JavaScript event-handler attributes of a MARQUEE element within a sandboxed IFRAME element that lacks the sandbox="allow-scripts" attribute value, which makes it easier for remote attackers to conduct cross-site scripting (XSS) attacks via a crafted web site.
Exploitability
AV:NAC:LPR:NUI:RScope
S:CImpact
C:LI:LA:N6.1/CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N