Mozilla Firefox < 86.0

high Nessus Plugin ID 146780


A web browser installed on the remote Windows host is affected by multiple vulnerabilities.


The version of Firefox installed on the remote Windows host is prior to 86.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2021-07 advisory.

- As specified in the W3C Content Security Policy draft, when creating a violation report, User agents need to ensure that the source file is the URL requested by the page, pre-redirects. If thats not possible, user agents need to strip the URL down to an origin to avoid unintentional leakage. Under certain types of redirects, Firefox incorrectly set the source file to be the destination of the redirects. This was fixed to be the redirect destination's origin. (CVE-2021-23969)

- Context-specific code was included in a shared jump table; resulting in assertions being triggered in multithreaded wasm code. (CVE-2021-23970)

- If Content Security Policy blocked frame navigation, the full destination of a redirect served in the frame was reported in the violation report; as opposed to the original frame URI. This could be used to leak sensitive information contained in such URIs. (CVE-2021-23968)

- The DOMParser API did not properly process <noscript> elements for escaping. This could be used as an mXSS vector to bypass an HTML Sanitizer. (CVE-2021-23974)

- When processing a redirect with a conflicting Referrer-Policy, Firefox would have adopted the redirect's Referrer-Policy. This would have potentially resulted in more information than intended by the original origin being provided to the destination of the redirect. (CVE-2021-23971)

- When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and allowed declaring webapp manifests for other origins. This could be used to gain fullscreen access for UI spoofing and could also lead to cross-origin attacks on targeted websites.Note: This issue is a different issue from CVE-2020-26954 and only affected Firefox for Android. Other operating systems are unaffected. (CVE-2021-23976)

- Firefox for Android suffered from a time-of-check-time-of-use vulnerability that allowed a malicious application to read sensitive data from application directories.Note: This issue is only affected Firefox for Android. Other operating systems are unaffected. (CVE-2021-23977)

- One phishing tactic on the web is to provide a link with HTTP Auth. For example https://[email protected] To mitigate this type of attack, Firefox will display a warning dialog; however, this warning dialog would not have been displayed if used a redirect that was cached by the browser. (CVE-2021-23972)

- The developer page about:memory has a Measure function for exploring what object types the browser has allocated and their sizes. When this function was invoked; we incorrectly called the sizeof function, instead of using the API method that checks for invalid pointers. (CVE-2021-23975)

- When trying to load a cross-origin resource in an audio/video context a decoding error may have resulted, and the content of that error may have revealed information about the resource. (CVE-2021-23973)

- Mozilla developers Alexis Beingessner, Tyson Smith, Nika Layzell, and Mats Palmgren reported memory safety bugs present in Firefox 85 and Firefox ESR 78.7. 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.

- Mozilla developers Tyson Smith, Lars T Hansen, Valentin Gosu, and Sebastian Hengst reported memory safety bugs present in Firefox 85. 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. (CVE-2021-23979)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.


Upgrade to Mozilla Firefox version 86.0 or later.

See Also

Plugin Details

Severity: High

ID: 146780

File Name: mozilla_firefox_86_0.nasl

Version: 1.6

Type: local

Agent: windows

Family: Windows

Published: 2/23/2021

Updated: 6/3/2021

Supported Sensors: Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent

Risk Information


Risk Factor: Medium

Score: 6.7


Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

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

Temporal Vector: E:U/RL:OF/RC:C

CVSS Score Source: CVE-2021-23979


Risk Factor: High

Base Score: 8.8

Temporal Score: 7.7

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:mozilla:firefox

Required KB Items: Mozilla/Firefox/Version

Exploit Ease: No known exploits are available

Patch Publication Date: 2/23/2021

Vulnerability Publication Date: 2/23/2021

Reference Information

CVE: CVE-2021-23968, CVE-2021-23969, CVE-2021-23970, CVE-2021-23971, CVE-2021-23972, CVE-2021-23973, CVE-2021-23974, CVE-2021-23975, CVE-2021-23976, CVE-2021-23977, CVE-2021-23978, CVE-2021-23979

IAVA: 2021-A-0107-S