CVE-2026-4706
Published: 24 March 2026
Summary
CVE-2026-4706 is a high-severity Improper Check for Unusual or Exceptional Conditions (CWE-754) vulnerability in Mozilla Firefox. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 7.3th 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 SI-2 (Flaw Remediation) and RA-5 (Vulnerability Monitoring and Scanning).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly addresses the CVE by requiring identification, reporting, and timely correction of the Canvas2D boundary condition flaw through patching to fixed Firefox and Thunderbird versions.
Facilitates detection of the known CVE-2026-4706 vulnerability in browser components via scanning to prioritize remediation efforts.
Ensures monitoring of vendor security advisories such as MFSA2026-20 to identify and apply patches for this DoS-causing boundary condition issue.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote exploitation of this Canvas2D boundary condition flaw directly triggers application crashes, matching T1499.004 (Application or System Exploitation) for endpoint denial of service with no C/I impact.
NVD Description
Incorrect boundary conditions in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Deeper analysisAI
CVE-2026-4706 involves incorrect boundary conditions in the Graphics: Canvas2D component, as documented under CWE-754. This vulnerability affects Mozilla Firefox versions prior to 149, Firefox ESR versions prior to 115.34 and 140.9, Thunderbird versions prior to 149, and Thunderbird versions prior to 140.9. It was published on 2026-03-24.
The vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Remote, unauthenticated attackers can exploit it over the network with low attack complexity and no user interaction required. Exploitation results in a denial-of-service condition with high availability impact, but no compromise of confidentiality or integrity.
Mozilla security advisories MFSA2026-20, MFSA2026-21, MFSA2026-22, and MFSA2026-23, along with Bugzilla entry 2015091, detail the issue. Mitigation involves updating to Firefox 149, Firefox ESR 115.34 or 140.9, Thunderbird 149, or Thunderbird 140.9, where the vulnerability has been fixed.
Details
- CWE(s)