Ubuntu: (Multiple Advisories) (CVE-2016-5824): Thunderbird vulnerabilities

A use-after-free was discovered in libical. If a user were tricked in to
opening a specially crafted ICS calendar file, an attacker could
potentially exploit this to cause a denial of service. (CVE-2016-5824)

Multiple security issues were discovered in Thunderbird. If a user were
tricked in to opening a specially crafted message, an attacker could
potentially exploit these to cause a denial of service, or execute
arbitrary code. (CVE-2018-18356, CVE-2018-18500, CVE-2019-5785)

Multiple security issues were discovered in Thunderbird. If a user were
tricked in to opening a specially crafted website in a browsing context,
an attacker could potentially exploit these to cause a denial of service,
gain additional privileges by escaping the sandbox, or execute arbitrary
code. (CVE-2018-18501, CVE-2018-18505)

An issue was discovered with S/MIME signature verification in some
circumstances. An attacker could potentially exploit this by spoofing
signatures for arbitrary content. (CVE-2018-18509)