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Bug 755170 (CVE-2020-16012, CVE-2020-26951, CVE-2020-26953, CVE-2020-26956, CVE-2020-26958, CVE-2020-26959, CVE-2020-26960, CVE-2020-26961, CVE-2020-26965, CVE-2020-26968, MFSA-2020-51)

Summary: <www-client/firefox{,-bin}-{78.5.0, 83}: Multiple vulnerabilities (MFSA-2020-51)
Product: Gentoo Security Reporter: Sam James <sam>
Component: VulnerabilitiesAssignee: Gentoo Security <security>
Severity: major CC: mozilla
Priority: Normal Keywords: CC-ARCHES
Version: unspecifiedFlags: nattka: sanity-check+
Hardware: All   
OS: Linux   
Whiteboard: A2 [glsa+ cve]
Package list:
Runtime testing required: ---

Description Sam James archtester Gentoo Infrastructure gentoo-dev Security 2020-11-17 22:14:46 UTC
* CVE-2020-26951

"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-2020-16012

"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."

* CVE-2020-26953

"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-2020-26956

"In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS."

* CVE-2020-26958

"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."

* CVE-2020-26959

"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."

* CVE-2020-26960

"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-2020-26961

"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."

* CVE-2020-26965

"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-2020-26968

"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."
Comment 1 NATTkA bot gentoo-dev 2020-11-17 22:16:49 UTC
Unable to check for sanity:

> no match for package: www-client/firefox-8.5.0
Comment 2 NATTkA bot gentoo-dev 2020-11-17 22:40:53 UTC
All sanity-check issues have been resolved
Comment 3 Sam James archtester Gentoo Infrastructure gentoo-dev Security 2020-11-19 00:20:32 UTC
arm64 done

all arches done
Comment 4 Larry the Git Cow gentoo-dev 2020-11-19 00:33:38 UTC
The bug has been referenced in the following commit(s):

commit 98afb81c74eae75712153527f6980e1b02a4a715
Author:     Thomas Deutschmann <>
AuthorDate: 2020-11-19 00:33:30 +0000
Commit:     Thomas Deutschmann <>
CommitDate: 2020-11-19 00:33:30 +0000

    www-client/firefox-bin: security cleanup
    Package-Manager: Portage-3.0.9, Repoman-3.0.2
    Signed-off-by: Thomas Deutschmann <>

 www-client/firefox-bin/Manifest                  | 194 -----------
 www-client/firefox-bin/firefox-bin-78.4.1.ebuild | 411 -----------------------
 www-client/firefox-bin/firefox-bin-82.0.3.ebuild | 411 -----------------------
 3 files changed, 1016 deletions(-)

commit f958b3aed74aa73666f364c7fad9864abded41e2
Author:     Thomas Deutschmann <>
AuthorDate: 2020-11-19 00:33:04 +0000
Commit:     Thomas Deutschmann <>
CommitDate: 2020-11-19 00:33:04 +0000

    www-client/firefox: security cleanup
    Package-Manager: Portage-3.0.9, Repoman-3.0.2
    Signed-off-by: Thomas Deutschmann <>

 www-client/firefox/Manifest              |  194 ------
 www-client/firefox/firefox-78.4.1.ebuild | 1120 ------------------------------
 www-client/firefox/firefox-82.0.3.ebuild | 1120 ------------------------------
 3 files changed, 2434 deletions(-)
Comment 5 GLSAMaker/CVETool Bot gentoo-dev 2020-12-07 00:37:38 UTC
This issue was resolved and addressed in
 GLSA 202012-03 at
by GLSA coordinator Thomas Deutschmann (whissi).