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, bypass same origin protections, or execute arbitrary code.
26 February 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, bypass same origin protections, or execute arbitrary code.
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.