#VU50880 Reachable Assertion in Mozilla Firefox - CVE-2021-23970

Vulnerability identifier: #VU50880

Vulnerability risk: Medium

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

CVE-ID: CVE-2021-23970

CWE-ID: CWE-617

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 a reachable assertion in multithreaded wasm code, when validating separation of script domains. A remote attacker can create a specially crafted web page, trick the victim into visiting it, trigger an assertion failure and bypass implemented security restrictions.

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.