When drawing a transparent image on top of an unknown cross-origin image, the
Skia library drawImage function took a variable amount of time depending on
the content of the underlying image. This resulted in potential cross-origin
information exposure of image content through timing side-channel attacks
A parsing and event loading mismatch in Firefox's SVG code could have allowed
load events to fire, even after sanitization. An attacker already capable of
exploiting an XSS vulnerability in privileged internal pages could have used
this attack to bypass our built-in sanitizer (CVE-2020-26951).
It was possible to cause the browser to enter fullscreen mode without
displaying the security UI; thus making it possible to attempt a phishing
attack or otherwise confuse the user (CVE-2020-26953).
In some cases, removing HTML elements during sanitization would keep existing
SVG event handlers and therefore lead to XSS (CVE-2020-26956).
Firefox did not block execution of scripts with incorrect MIME types when the
response was intercepted and cached through a ServiceWorker. This could lead
to a cross-site script inclusion vulnerability, or a Content Security Policy
During browser shutdown, reference decrementing could have occured on a
previously freed object, resulting in a use-after-free in WebRequestService,
memory corruption, and a potentially exploitable crash (CVE-2020-26959).
If the Compact() method was called on an nsTArray, the array could have been
reallocated without updating other pointers, leading to a potential
use-after-free and exploitable crash (CVE-2020-26960).
When DNS over HTTPS is in use, it intentionally filters RFC1918 and related IP
ranges from the responses as these do not make sense coming from a DoH
resolver. However when an IPv4 address was mapped through IPv6, these
addresses were erroneously let through, leading to a potential DNS Rebinding
Some websites have a feature "Show Password" where clicking a button will
change a password field into a textbook field, revealing the typed password.
If, when using a software keyboard that remembers user input, a user typed
their password and used that feature, the type of the password field was
changed, resulting in a keyboard layout change and the possibility for the
software keyboard to remember the typed password (CVE-2020-26965).
Mozilla developers Steve Fink, Jason Kratzer, Randell Jesup, Christian Holler,
and Byron Campen reported memory safety bugs present in Firefox ESR 78.4. Some
of these bugs showed evidence of memory corruption and we presume that with
enough effort some of these could have been exploited to run arbitrary code