Firefox could be made to crash or run programs as your login if it opened a malicious website.
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, gain additional privileges by escaping the sandbox, or execute arbitrary code. (CVE-2018-18500, CVE-2018-18501, CVE-2018-18502, CVE-2018-18503, CVE-2018-18504, CVE-2018-18505)
30 January 2019
A security issue affects these releases of Ubuntu and its derivatives:
Firefox could be made to crash or run programs as your login if it opened a malicious website.
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, gain additional privileges by escaping the sandbox, or execute arbitrary code. (CVE-2018-18500, CVE-2018-18501, CVE-2018-18502, CVE-2018-18503, CVE-2018-18504, CVE-2018-18505)
It was discovered that Firefox allowed PAC files to specify that requests to localhost are sent through the proxy to another server. If proxy auto-detection is enabled, an attacker could potentially exploit this to conduct attacks on local services and tools. (CVE-2018-18506)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to restart Firefox to make all the necessary changes.