USN-3435-1 caused a regression in Firefox.
USN-3435-1 fixed vulnerabilities in Firefox. The update caused the Flash plugin to crash in some circumstances. This update fixes the problem.
4 October 2017
A security issue affects these releases of Ubuntu and its derivatives:
USN-3435-1 caused a regression in Firefox.
USN-3435-1 fixed vulnerabilities in Firefox. The update caused the Flash plugin to crash in some circumstances. This update fixes the problem.
We apologize for the inconvenience.
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 read uninitialized memory, obtain sensitive information, bypass phishing and malware protection, spoof the origin in modal dialogs, conduct cross-site scripting (XSS) attacks, cause a denial of service via application crash, or execute arbitrary code. (CVE-2017-7793, CVE-2017-7810, CVE-2017-7811, CVE-2017-7812, CVE-2017-7813, CVE-2017-7814, CVE-2017-7815, CVE-2017-7818, CVE-2017-7819, CVE-2017-7820, CVE-2017-7822, CVE-2017-7823, CVE-2017-7824)
Martin Thomson discovered that NSS incorrectly generated handshake hashes. A remote attacker could potentially exploit this to cause a denial of service via application crash, or execute arbitrary code. (CVE-2017-7805)
Multiple security issues were discovered in WebExtensions. If a user were tricked in to installing a specially crafted extension, an attacker could potentially exploit these to download and open non-executable files without interaction, or obtain elevated privileges. (CVE-2017-7816, CVE-2017-7821)
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