#VU29457 Improper Certificate Validation in Mozilla Firefox and Firefox ESR - CVE-2020-12421

Vulnerability identifier: #VU29457

Vulnerability risk: Low

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

CVE-ID: CVE-2020-12421

CWE-ID: CWE-295

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 disable installed Add-Ons.

The vulnerability exists due to Add-On updates do not respect the same certificate trust rules as software updates. When performing add-on updates, certificate chains terminating in non-built-in-roots were rejected (even if they were legitimately added by an administrator.) This could have caused add-ons to become out-of-date silently without notification to the user.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 60.0 - 77.0.1

Firefox ESR: 60.0 - 60.9.0, 68.0 - 68.9.0

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2020-25/
https://www.mozilla.org/en-US/security/advisories/mfsa2020-24/

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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.