Vulnerability identifier: #VU58611

Vulnerability risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-43541

CWE-ID: CWE-20

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 bypass implemented security restrictions.

The vulnerability exists due to insufficient validation of user-supplied input when handling spaces in URLS with external protocol handlers. A remote attacker can trick the victim to click on a specially crafted link and pass unescaped input to a third-party application via URI handler.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 90.0 - 94.0.2

Firefox ESR: 91.0 - 91.3.0

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-52/
http://www.mozilla.org/en-US/security/advisories/mfsa2021-53/

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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.