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Ubuntu Security Notice USN-3435-2
October 04, 2017

firefox regression
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 17.04
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

USN-3435-1 caused a regression in Firefox.

Software Description:
- firefox: Mozilla Open Source web browser

Details:

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)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 17.04:
  firefox                         56.0+build6-0ubuntu0.17.04.2

Ubuntu 16.04 LTS:
  firefox                         56.0+build6-0ubuntu0.16.04.2

Ubuntu 14.04 LTS:
  firefox                         56.0+build6-0ubuntu0.14.04.2

After a standard system update you need to restart Firefox to make
all the necessary changes.

References:
  https://www.ubuntu.com/usn/usn-3435-2
  https://www.ubuntu.com/usn/usn-3435-1
  https://launchpad.net/bugs/1720908

Package Information:
  https://launchpad.net/ubuntu/+source/firefox/56.0+build6-0ubuntu0.17.04.2
  https://launchpad.net/ubuntu/+source/firefox/56.0+build6-0ubuntu0.16.04.2
  https://launchpad.net/ubuntu/+source/firefox/56.0+build6-0ubuntu0.14.04.2