Vulnerability identifier: #VU77002

Vulnerability risk: Medium

CVSSv3.1: 5.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-34414

CWE-ID: CWE-451

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 perform spoofing attack.

The vulnerability exists due to incorrect processing of user-supplied data when displaying certificate exceptions. The error page for sites with invalid TLS certificates was missing the activation-delay Firefox uses to protect prompts and permission dialogs from attacks that exploit human response time delays. If a malicious page elicited user clicks in precise locations immediately before navigating to a site with a certificate error and made the renderer extremely busy at the same time, it could create a gap between when the error page was loaded and when the display actually refreshed.

With the right timing the elicited clicks could land in that gap and activate the button that overrides the certificate error for that site.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 100.0 - 113.0.2

Firefox ESR: 102.0 - 102.11.0

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2023-20/
http://www.mozilla.org/en-US/security/advisories/mfsa2023-19/

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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.