#VU111887 Insufficient UI Warning of Dangerous Operations in Firefox ESR and Mozilla Firefox - CVE-2025-6426

Vulnerability identifier: #VU111887

Vulnerability risk: High

CVSSv4.0: 4.8 [CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-6426

CWE-ID: CWE-357

Exploitation vector: Network

Exploit availability: No

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

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to the terminal extension does not show a warning when opening an executable terminal filer on macOS. A remote attacker can trick the victim into executing an executable file and compromise the affected system.

Note, the vulnerability affects macOS installations only. 

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Firefox ESR: 128.0, 128.1.0, 128.2.0, 128.3.0, 128.3.1, 128.4.0, 128.5.0, 128.5.1, 128.5.2, 128.6.0, 128.7.0, 128.8.0, 128.8.1, 128.9.0, 128.10.0, 128.10.1, 128.11.0

Mozilla Firefox: 128.0 - 139.0.4

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2025-53/
https://www.mozilla.org/en-US/security/advisories/mfsa2025-51/
https://bugzilla.mozilla.org/show_bug.cgi?id=1964385

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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.