Vulnerability identifier: #VU50022

Vulnerability risk: High

CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-23954

CWE-ID: CWE-843

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers
Firefox ESR
Client/Desktop applications / Web browsers

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a type confusion error when using the new logical assignment operators in a JavaScript switch statement. A remote attacker can create a specially crafted web page, trick the victim into opening it, trigger a type confusion error and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 60.0 - 84.0.2

Firefox ESR: 78.0 - 78.6.1, 68.0 - 68.12.0, 60.0 - 60.9.0

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-03/
http://www.mozilla.org/en-US/security/advisories/mfsa2021-04/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.