CVE-2026-2759
Published: 24 February 2026
Summary
CVE-2026-2759 is a critical-severity Improper Handling of Physical or Environmental Conditions (CWE-1384) 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 31.5th 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 SI-10 (Information Input Validation).
Deeper analysis
CVE-2026-2759 involves incorrect boundary conditions in the Graphics: ImageLib component of Mozilla products. It affects Firefox versions prior to 148, Firefox ESR versions prior to 115.33 and 140.8, Thunderbird versions prior to 148, and Thunderbird versions prior to 140.8. The vulnerability is associated with CWE-1384 and has a CVSS v3.1 base score of 9.8.
Remote attackers require no privileges or user interaction to exploit this vulnerability over the network with low attack complexity. Successful exploitation can result in high impacts to confidentiality, integrity, and availability, potentially enabling arbitrary code execution within the affected browser or mail client context.
Mozilla addressed the issue in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8. Further details on the patches and remediation are provided in Mozilla Security Advisories MFSA2026-13, MFSA2026-14, MFSA2026-15, and MFSA2026-16, as well as Bugzilla entry 2010933.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8481
Vulnerability details
Incorrect boundary conditions in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote RCE in browser/email client image library (no privileges or interaction required) directly enables drive-by website compromise and exploitation for client-side code execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requires timely remediation of flaws, directly addressing this boundary condition vulnerability through patching to fixed Firefox and Thunderbird versions.
Provides memory protections like ASLR and DEP to mitigate exploitation of boundary condition errors leading to arbitrary code execution in ImageLib.
Mandates validation of information inputs such as image data to prevent boundary condition violations in the Graphics: ImageLib component.