Ubuntu Security Notice 4893-1 - Multiple security issues were
discovered in Firefox. If a user were tricked into opening a
specially crafted website, an attacker could potentially exploit
these to cause a denial of service, obtain sensitive information,
or execute arbitrary code. It was discovered that extensions could
open popup windows with control of the window title in some
circumstances. If a user were tricked into installing a specially
crafted extension, an attacker could potentially exploit this to
spook a website and trick the user into providing credentials.
Various other issues were also addressed.
Ubuntu Security Notice 4893-1 - Multiple security issues were
discovered in Firefox. If a user were tricked into opening a
specially crafted website, an attacker could potentially exploit
these to cause a denial of service, obtain sensitive information,
or execute arbitrary code. It was discovered that extensions could
open popup windows with control of the window title in some
circumstances. If a user were tricked into installing a specially
crafted extension, an attacker could potentially exploit this to
spook a website and trick the user into providing credentials.
Various other issues were also addressed.
Read more https://packetstormsecurity.com/files/161992/USN-4893-1.txt

