Debian Security Advisory

DSA-5026-1 firefox-esr -- security update

Date Reported:
19 Dec 2021
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-2021-43546, CVE-2021-43545, CVE-2021-43543, CVE-2021-43542, CVE-2021-43541, CVE-2021-43539, CVE-2021-43538, CVE-2021-43537, CVE-2021-43536, CVE-2021-43535, CVE-2021-43534, CVE-2021-38509, CVE-2021-38508, CVE-2021-38507, CVE-2021-38506, CVE-2021-38504, CVE-2021-38503.
More information:

Multiple security issues have been found in the Mozilla Firefox web browser, which could potentially result in the execution of arbitrary code, information disclosure or spoofing.

Debian follows the extended support releases (ESR) of Firefox. Support for the 78.x series has ended, so starting with this update we're now following the 91.x releases.

Between 78.x and 91.x, Firefox has seen a number of feature updates. For more information please refer to

For the oldstable distribution (buster) one more final toolchain update is needed, updated packages will shortly be available as 91.4.1esr-1~deb10u1

For the stable distribution (bullseye), these problem have been fixed in version 91.4.1esr-1~deb11u1.

We recommend that you upgrade your firefox-esr packages.

For the detailed security status of firefox-esr please refer to its security tracker page at: