Security Alert (A26-03-26): Multiple Vulnerabilities in Firefox

Description:

Mozilla has published the advisories (MFSA2026-20, MFSA2026-21 and MFSA2026-22) to address multiple vulnerabilities in Firefox. A remote attacker could entice a user to open a web page with specially crafted content on a vulnerable browser to exploit the vulnerabilities.

Affected Systems:

• Firefox ESR Windows versions prior to version 115.34, 140.9
• Firefox Windows versions prior to version 149

For detailed information of the affected systems, please refer to the corresponding security advisories at vendor's website.

Impact:

Successful exploitation of the vulnerabilities could lead to remote code execution, denial of service, elevation of privilege, information disclosure, security restriction bypass or spoofing on an affected system.

Recommendation:

Mozilla has released new versions of the product to address the issues and they can be downloaded at the following URLs:
Firefox 149 (Windows)
https://www.mozilla.org/en-US/firefox/all/#product-desktop-release
Firefox ESR 115.34, 140.9 (Windows)
https://www.mozilla.org/en-US/firefox/all/#product-desktop-esr

Users of affected systems should follow the recommendations provided by the vendor and take immediate actions to mitigate the risk.

More Information:

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-20/
• https://www.mozilla.org/en-US/security/advisories/mfsa2026-21/
• https://www.mozilla.org/en-US/security/advisories/mfsa2026-22/
• https://www.hkcert.org/security-bulletin/mozilla-products-multiple-vulnerabilities_20260325
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-59375
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-4684 (to CVE-2026-4702)
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-4704 (to CVE-2026-4729)