Ubuntu: USN-4991-1 (CVE-2017-8872): libxml2 vulnerabilities

Yunho Kim discovered that libxml2 incorrectly handled certain error
conditions. A remote attacker could exploit this with a crafted XML file to
cause a denial of service, or possibly cause libxml2 to expose sensitive
information. This issue only affected Ubuntu 14.04 ESM, and Ubuntu 16.04
ESM. (CVE-2017-8872)

Zhipeng Xie discovered that libxml2 incorrectly handled certain XML
schemas. A remote attacker could possibly use this issue to cause a denial
of service. This issue only affected Ubuntu 14.04 ESM, Ubuntu 16.04 ESM,
and Ubuntu 18.04 LTS. (CVE-2019-20388)

It was discovered that libxml2 incorrectly handled invalid UTF-8 input. A
remote attacker could possibly exploit this with a crafted XML file to
cause libxml2 to crash, resulting in a denial of service. This issue only
affected Ubuntu 14.04 ESM, Ubuntu 16.04 ESM, Ubuntu 18.04 LTS, Ubuntu 20.04
LTS and Ubuntu 20.10. (CVE-2020-24977)

It was discovered that libxml2 incorrectly handled invalid UTF-8 input. A
remote attacker could possibly exploit this with a crafted XML file to
cause libxml2 to crash, resulting in a denial of service. (CVE-2021-3517)

It was discovered that libxml2 did not properly handle certain crafted XML
files. A local attacker could exploit this with a crafted input to cause
libxml2 to crash, resulting in a denial of service, or possibly execute
arbitrary code. (CVE-2021-3516, CVE-2021-3518)

It was discovered that libxml2 incorrectly handled error states. A remote
attacker could exploit this with a crafted XML file to cause libxml2 to
crash, resulting in a denial of service. (CVE-2021-3537)

Sebastian Pipping discovered that libxml2 did not properly handle certain
crafted XML files. A remote attacker could exploit this with a crafted XML
file to cause libxml2 to crash, resulting in a denial of service. This
issue only affected Ubuntu 20.04 LTS, Ubuntu 20.10, and Ubuntu 21.04.
(CVE-2021-3541)