CVE-2026-2762
Published: 24 February 2026
Summary
CVE-2026-2762 is a critical-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 41.6th 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).
Deeper analysis
CVE-2026-2762 is an integer overflow vulnerability (CWE-190) in the JavaScript Standard Library component of Mozilla products. It affects Firefox versions prior to 148, Firefox ESR prior to 140.8, Thunderbird prior to 148, and Thunderbird prior to 140.8.
The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating that a remote attacker requires no privileges or user interaction to exploit it over the network with low complexity. Successful exploitation can result in high impacts to confidentiality, integrity, and availability, potentially allowing arbitrary code execution within the browser or mail client context.
Mozilla addressed the issue in the specified fixed releases, as detailed in security advisories MFSA 2026-13, MFSA 2026-15, MFSA 2026-16, and MFSA 2026-17, along with Bugzilla entry 2011649. Security practitioners should ensure affected products are updated to patched versions to mitigate the risk.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8484
Vulnerability details
Integer overflow in the JavaScript: Standard Library component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Integer overflow in JS Standard Library enables remote arbitrary code execution in browser/mail client (no auth/UI required), directly facilitating drive-by compromise via malicious sites and exploitation for client execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely identification, reporting, testing, and installation of patches for known flaws like the integer overflow in Mozilla's JavaScript Standard Library.
Mandates vulnerability scanning to identify systems running vulnerable versions of Firefox and Thunderbird prior to the fixed releases.
Ensures receipt and dissemination of security advisories like MFSA 2026-13 through 17, enabling prompt awareness and patching of this CVE.