CVE-2026-4712
Published: 24 March 2026
Summary
CVE-2026-4712 is a high-severity Exposure of Sensitive Information to an Unauthorized Actor (CWE-200) vulnerability in Mozilla Firefox. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 4.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly mandates timely patching of known flaws like CVE-2026-4712, as fixed in specified Firefox and Thunderbird versions.
Enables vulnerability scanning to identify systems running vulnerable versions of Firefox, ESR, or Thunderbird affected by this information disclosure.
Requires monitoring Mozilla security advisories (e.g., MFSA 2026-20) to promptly learn of and apply patches for this CVE.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated info disclosure (CWE-200) with high confidentiality impact directly enables collection of sensitive data from the local system on affected browsers/email clients.
NVD Description
Information disclosure in the Widget: Cocoa component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Deeper analysisAI
CVE-2026-4712 is an information disclosure vulnerability (CWE-200) in the Widget: Cocoa component, affecting Mozilla Firefox, Firefox ESR, and Thunderbird. The issue enables unauthorized access to sensitive data and was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Remote attackers can exploit this vulnerability over the network with low attack complexity, requiring no privileges, no user interaction, and without altering the scope of impact. Successful exploitation results in high confidentiality impact, allowing disclosure of sensitive information from affected systems, while integrity and availability remain unaffected. The CVSS v3.1 base score is 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).
Mozilla's security advisories (MFSA 2026-20, MFSA 2026-22, MFSA 2026-23, and MFSA 2026-24), along with Bugzilla entry 2017666, document the vulnerability and recommend updating to the patched versions as the primary mitigation.
Details
- CWE(s)