Ubuntu: (Multiple Advisories) (CVE-2015-8853): Perl vulnerabilities

It was discovered that Perl incorrectly handled certain regular
expressions. An attacker could possibly use this issue to cause Perl to
hang, resulting in a denial of service. This issue only affected Ubuntu
14.04 LTS. (CVE-2015-8853)

It was discovered that Perl incorrectly loaded libraries from the current
working directory. A local attacker could possibly use this issue to
execute arbitrary code. This issue only affected Ubuntu 14.04 LTS and
Ubuntu 16.04 LTS. (CVE-2016-6185)

It was discovered that Perl incorrectly handled the rmtree and remove_tree
functions. A local attacker could possibly use this issue to set the mode
on arbitrary files. This issue only affected Ubuntu 14.04 LTS and Ubuntu
16.04 LTS. (CVE-2017-6512)

Brian Carpenter discovered that Perl incorrectly handled certain regular
expressions. An attacker could use this issue to cause Perl to crash,
resulting in a denial of service, or possibly execute arbitrary code. This
issue has only been addressed in Ubuntu 16.04 LTS and Ubuntu 17.10.
(CVE-2018-6797)

Nguyen Duc Manh discovered that Perl incorrectly handled certain regular
expressions. An attacker could use this issue to cause Perl to crash,
resulting in a denial of service. This issue only affected Ubuntu 16.04 LTS
and Ubuntu 17.10. (CVE-2018-6798)

GwanYeong Kim discovered that Perl incorrectly handled certain data when
using the pack function. An attacker could use this issue to cause Perl to
crash, resulting in a denial of service, or possibly execute arbitrary
code. (CVE-2018-6913)