Description

Clickjacking issue in the DOM: Events component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

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References

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=2060153 https://www.mozilla.org/security/advisories/mfsa2026-82/ https://www.mozilla.org/security/advisories/mfsa2026-85/ https://www.mozilla.org/security/advisories/mfsa2026-86/ https://www.mozilla.org/security/advisories/mfsa2026-88/

Frequently Asked Questions

What is CVE-2026-84139? +

Clickjacking issue in the DOM: Events component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

How do I check if I'm vulnerable to CVE-2026-84139? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.