#VU50882 Cross-site scripting in Mozilla Firefox - CVE-2021-23974

Vulnerability identifier: #VU50882

Vulnerability risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-23974

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

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

Vendor: Mozilla

Description

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data. The DOMParser API did not properly process <noscript> elements for escaping. A remote attacker can bypass HTML Sanitizer and perform XSS attacks.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 80.0 - 85.0.2

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2021-07/

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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.