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mozillaMozilla FoundationMFSA2020-51
HistoryNov 17, 2020 - 12:00 a.m.

Security Vulnerabilities fixed in Firefox ESR 78.5 — Mozilla

2020-11-1700:00:00
Mozilla Foundation
www.mozilla.org
97

CVSS2

9.3

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:N/AC:M/Au:N/C:C/I:C/A:C

CVSS3

8.8

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

0.026

Percentile

90.3%

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.
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.
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.
In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS.
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 bypass.
During browser shutdown, reference decrementing could have occured on a previously freed object, resulting in a use-after-free, memory corruption, and a potentially exploitable crash.
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.
In Freetype, if PNG images were embedded into fonts, the Load_SBit_Png function contained an integer overflow that led to a heap buffer overflow, memory corruption, and an exploitable crash.Note: While Project Zero did discover instances of this vulnerability being exploited in the wild against Chrome, in Firefox this vulnerability is only triggerable if a rarely-used, hidden preference is toggled, and only affected Linux and Android operating systems. Other operating systems are unaffected; and Linux and Android are unaffected in the default configuration.
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 attack.
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.
Searching for a single word from the address bar caused an mDNS request to be sent on the local network searching for a hostname consisting of that string; resulting in an information leak.Note: This issue only affected Windows operating systems. Other operating systems are unaffected.
Mozilla developers Steve Fink, Jason Kratzer, Randell Jesup, Christian Holler, and Byron Campen reported memory safety bugs present in Firefox 82 and 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.

Affected configurations

Vulners
Node
mozillafirefox_esrRange<78.5
CPENameOperatorVersion
firefox esrlt78.5

CVSS2

9.3

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:N/AC:M/Au:N/C:C/I:C/A:C

CVSS3

8.8

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

0.026

Percentile

90.3%