USN-3918-2: Firefox vulnerabilities

USN-3918-1 fixed vulnerabilities in Firefox. This update provides the corresponding updates for Ubuntu 14.04 LTS. Original advisory details: Multiple security issues were discovered in Firefox. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit these to cause a denial of service via application crash, denial of service via successive FTP authorization prompts or modal alerts, trick the user with confusing permission request prompts, obtain sensitive information, conduct social engineering attacks, or execute arbitrary code. (CVE-2019-9788, CVE-2019-9789, CVE-2019-9790, CVE-2019-9791, CVE-2019-9792, CVE-2019-9795, CVE-2019-9796, CVE-2019-9797, CVE-2019-9799, CVE-2019-9802, CVE-2019-9805, CVE-2019-9806, CVE-2019-9807, CVE-2019-9808, CVE-2019-9809) A mechanism was discovered that removes some bounds checking for string, array, or typed array accesses if Spectre mitigations have been disabled. If a user were tricked in to opening a specially crafted website with Spectre mitigations disabled, an attacker could potentially exploit this to cause a denial of service, or execute arbitrary code. (CVE-2019-9793) It was discovered that Upgrade-Insecure-Requests was incorrectly enforced for same-origin navigation. An attacker could potentially exploit this to conduct machine-in-the-middle (MITM) attacks. (CVE-2019-9803)