Ubuntu Security Notice USN-3918-3

Ubuntu Security Notice USN-3918-3
March 28, 2019

firefox regression

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

– Ubuntu 18.10
– Ubuntu 18.04 LTS
– Ubuntu 16.04 LTS
– Ubuntu 14.04 LTS


USN-3918-1 caused a regression in Firefox.

Software Description:
– firefox: Mozilla Open Source web browser


USN-3918-1 fixed vulnerabilities in Firefox. The update caused web
compatibility issues with some websites. 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 cause a denial of service via application
crash, denial of service via successive FTP authorization prompts or modal
alerts, trick the user with confusing permission request prompts, obtain
sensitive information, conduct social engineering attacks, or execute
arbitrary code. (CVE-2019-9788, CVE-2019-9789, CVE-2019-9790,
CVE-2019-9791, CVE-2019-9792, CVE-2019-9795, CVE-2019-9796, CVE-2019-9797,
CVE-2019-9799, CVE-2019-9802, CVE-2019-9805, CVE-2019-9806, CVE-2019-9807,
CVE-2019-9808, CVE-2019-9809)

A mechanism was discovered that removes some bounds checking for string,
array, or typed array accesses if Spectre mitigations have been disabled.
If a user were tricked in to opening a specially crafted website with
Spectre mitigations disabled, an attacker could potentially exploit this
to cause a denial of service, or execute arbitrary code. (CVE-2019-9793)

It was discovered that Upgrade-Insecure-Requests was incorrectly enforced
for same-origin navigation. An attacker could potentially exploit this to
conduct man-in-the-middle (MITM) attacks. (CVE-2019-9803)

Update instructions:

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

Ubuntu 18.10:
firefox 66.0.2+build1-0ubuntu0.18.10.1

Ubuntu 18.04 LTS:
firefox 66.0.2+build1-0ubuntu0.18.04.1

Ubuntu 16.04 LTS:
firefox 66.0.2+build1-0ubuntu0.16.04.1

Ubuntu 14.04 LTS:
firefox 66.0.2+build1-0ubuntu0.14.04.1

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


Package Information: