Vulnerability identifier: #VU58610

Vulnerability risk: Medium

CVSSv3.1: 4.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-43540

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: No

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

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to an error with WebExtensions that causes a WebExtension with the correct permissions to create and install ServiceWorkers for third-party websites that cannot be uninstalled with the extension.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 90.0 - 94.0.2

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-52/

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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.