Information Disclosure in Firefox Browser by Mozilla
CVE-2026-4712

7.5HIGH

Key Information:

Vendor

Mozilla
Status
Firefox
Firefox Esr
Thunderbird
Vendor
CVE Published:
24 March 2026

What is CVE-2026-4712?

This vulnerability involves information disclosure in the Widget: Cocoa component of Mozilla's Firefox browser, affecting versions prior to Firefox 149 and Firefox ESR versions less than 140.9. Exploitation of this flaw could allow attackers to access sensitive data which could compromise user privacy and security. Users are advised to upgrade to the latest versions to mitigate this risk.

Affected Version(s)

Firefox < 149

Firefox ESR < 140.9

Thunderbird < 149

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2017666
https://www.mozilla.org/security/advisories/mfsa2026-20/
https://www.mozilla.org/security/advisories/mfsa2026-22/

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Josh Aas
.