Ubuntu: (Multiple Advisories) (CVE-2017-8834): Libcroco vulnerabilities

It was discovered that Libcroco was incorrectly accessing data structures when
reading bytes from memory, which could cause a heap buffer overflow. An attacker
could possibly use this issue to cause a denial of service. (CVE-2017-7960)

It was discovered that Libcroco was incorrectly handling invalid UTF-8 values
when processing CSS files. An attacker could possibly use this issue to cause
a denial of service. (CVE-2017-8834, CVE-2017-8871)

It was discovered that Libcroco was incorrectly implementing recursion in one
of its parsing functions, which could cause an infinite recursion loop and a
stack overflow due to stack consumption. An attacker could possibly use this
issue to cause a denial of service. (CVE-2020-12825)