What is CVE-2021-23986?

CVE-2021-23986 is a vulnerability in Mozilla Firefox which allows a malicious extension with the 'search' permission to install a new search engine with a cross-origin favicon that could be read by the extension, bypassing the same-origin policy.

What is the severity of CVE-2021-23986?

The severity of CVE-2021-23986 is medium, with a severity value of 6.5.

Which software is affected by CVE-2021-23986?

Mozilla Firefox versions up to exclusive 87.0 are affected by CVE-2021-23986.

How can the CVE-2021-23986 vulnerability be fixed?

To fix the CVE-2021-23986 vulnerability, users should update to Mozilla Firefox version 87.0 or later.

What is the CWE classification of CVE-2021-23986?

CVE-2021-23986 is classified as CWE-346, which is for incorrect generation of URLs that allow unintended access to a resource.

Vulnerability/
CVE-2021-23986

medium

6.5

CWE

346

23/3/2021

31/3/2021

3/8/2024

CVE-2021-23986

First published: Tue Mar 23 2021(Updated: )

A malicious extension with the 'search' permission could have installed a new search engine whose favicon referenced a cross-origin URL. The response to this cross-origin request could have been read by the extension, allowing a same-origin policy bypass by the extension, which should not have cross-origin permissions. This cross-origin request was made without cookies, so the sensitive information disclosed by the violation was limited to local-network resources or resources that perform IP-based authentication.

Credit: security@mozilla.org

Affected Software	Affected Version	How to fix
Mozilla Firefox	<87	87
	<87	87
Mozilla Firefox	<87.0

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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

MFSA2021-10

Peer vulnerabilities

(Found alongside the following vulnerabilities)

Frequently Asked Questions

What is CVE-2021-23986?
CVE-2021-23986 is a vulnerability in Mozilla Firefox which allows a malicious extension with the 'search' permission to install a new search engine with a cross-origin favicon that could be read by the extension, bypassing the same-origin policy.
What is the severity of CVE-2021-23986?
The severity of CVE-2021-23986 is medium, with a severity value of 6.5.
Which software is affected by CVE-2021-23986?
Mozilla Firefox versions up to exclusive 87.0 are affected by CVE-2021-23986.
How can the CVE-2021-23986 vulnerability be fixed?
To fix the CVE-2021-23986 vulnerability, users should update to Mozilla Firefox version 87.0 or later.
What is the CWE classification of CVE-2021-23986?
CVE-2021-23986 is classified as CWE-346, which is for incorrect generation of URLs that allow unintended access to a resource.

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