Firefox could be made to expose sensitive information.
It was discovered that speculative execution performed by modern CPUs could leak information through a timing side-channel attack, and that this could be exploited in web browser JavaScript engines. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit this to obtain sensitive information from other domains, bypassing same-origin restrictions. (CVE-2017-5715, CVE-2017-5753, CVE-2017-5754).
5 January 2018
A security issue affects these releases of Ubuntu and its derivatives:
Firefox could be made to expose sensitive information.
It was discovered that speculative execution performed by modern CPUs could leak information through a timing side-channel attack, and that this could be exploited in web browser JavaScript engines. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit this to obtain sensitive information from other domains, bypassing same-origin restrictions. (CVE-2017-5715, CVE-2017-5753, CVE-2017-5754).
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.
Vulmon