USN-3596-1: Firefox vulnerabilities

It was discovered that the value of app.support.baseURL is not sanitized properly. If a malicious local application were to set this to a specially crafted value, an attacker could potentially exploit this to execute arbitrary code. (CVE-2018-5133)

It was discovered that javascript: URLs with embedded tab characters could be pasted in to the addressbar. If a user were tricked in to copying a specially crafted URL in to the addressbar, an attacker could exploit this to conduct cross-site scripting (XSS) attacks. (CVE-2018-5143)

REF: https://usn.ubuntu.com/3596-1/