CVE-2026-2760
Published: 24 February 2026
Summary
CVE-2026-2760 is a critical-severity Improper Handling of Physical or Environmental Conditions (CWE-1384) vulnerability in Mozilla Firefox. Its CVSS base score is 10.0 (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 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-2760 is a sandbox escape vulnerability stemming from incorrect boundary conditions in the Graphics: WebRender component of Mozilla Firefox and Thunderbird. It affects versions of Firefox prior to 148, Firefox ESR prior to 115.33 and 140.8, Thunderbird prior to 148, and Thunderbird prior to 140.8. The issue is cataloged under CWE-1384 with an NVD-CWE-noinfo mapping and carries a maximum CVSS v3.1 base score of 10.0 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H), indicating critical severity due to its network accessibility, low attack complexity, and lack of prerequisites.
Remote attackers can exploit this vulnerability over the network without user privileges or interaction, leveraging malicious web content to bypass the browser's sandbox isolation in the WebRender graphics rendering engine. Successful exploitation enables scope change with high impacts on confidentiality, integrity, and availability, potentially granting attackers full control over the affected browser process and leading to arbitrary code execution on the user's system.
Mozilla's security advisories (MFSA 2026-13 through 2026-16) and the associated Bugzilla entry (bug 2011062) detail the fix applied in the specified versions of Firefox and Thunderbird. Security practitioners should prioritize updating affected browsers to mitigate this risk, as no workarounds are mentioned in the provided references.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8482
Vulnerability details
Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender 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?
Sandbox escape via malicious web content enables drive-by compromise (T1189) and client execution (T1203); scope-changing sandbox bypass constitutes privilege escalation (T1068) to achieve RCE.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mitigates CVE-2026-2760 by requiring timely patching of the sandbox escape flaw in Firefox and Thunderbird's WebRender component.
Identifies systems running vulnerable versions of Firefox prior to 148, ESR prior to 115.33/140.8, or Thunderbird prior to 148/140.8 through vulnerability scanning.
Provides additional protection against exploitation of the sandbox escape via malicious web content through malicious code detection and eradication mechanisms.