USN-3477-3: Firefox regressions

Ubuntu Security Notice USN-3477-3

1st December, 2017

firefox regressions

A security issue affects these releases of Ubuntu and its

  • Ubuntu 17.10
  • Ubuntu 17.04
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS


USN-3477-1 caused some minor regressions in Firefox.

Software description

  • firefox
    – Mozilla Open Source web browser


USN-3477-1 fixed vulnerabilities in Firefox. The update introduced various
minor regressions. This update fixes the problems.

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 cause a denial of service, read uninitialized
memory, obtain sensitive information, bypass same-origin restrictions,
bypass CSP protections, bypass mixed content blocking, spoof the
addressbar, or execute arbitrary code. (CVE-2017-7826, CVE-2017-7827,
CVE-2017-7828, CVE-2017-7830, CVE-2017-7831, CVE-2017-7832, CVE-2017-7833,
CVE-2017-7834, CVE-2017-7835, CVE-2017-7837, CVE-2017-7838, CVE-2017-7842)

It was discovered that javascript: URLs pasted in to the addressbar
would be executed instead of being blocked in some circumstances. If a
user were tricked in to copying a specially crafted URL in to the
addressbar, an attacker could potentially exploit this to conduct
cross-site scripting (XSS) attacks. (CVE-2017-7839)

It was discovered that exported bookmarks do not strip script elements
from user-supplied tags. If a user were tricked in to adding specially
crafted tags to bookmarks, exporting them and then opening the resulting
HTML file, an attacker could potentially exploit this to conduct
cross-site scripting (XSS) attacks. (CVE-2017-7840)

Update instructions

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

Ubuntu 17.10:

Ubuntu 17.04:

Ubuntu 16.04 LTS:

Ubuntu 14.04 LTS:


To update your system, please follow these instructions:

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


LP: 1735801

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