CVE-2026-2780
Published: 24 February 2026
Summary
CVE-2026-2780 is a critical-severity Improper Privilege Management (CWE-269) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 5.4th 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 SI-2 (Flaw Remediation) and AC-3 (Access Enforcement).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly mitigates the privilege escalation vulnerability by requiring timely remediation through patching to Firefox 148, Firefox ESR 140.8, Thunderbird 148, or Thunderbird 140.8.
Addresses improper privilege management (CWE-269) by enforcing least privilege on the Netmonitor component to limit escalation impact.
Enforces access control policies to counter unauthorized privilege escalation in the Netmonitor component.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE describes a remote privilege escalation vulnerability (CWE-269) in a client application that directly enables T1068 Exploitation for Privilege Escalation, leading to full system compromise.
NVD Description
Privilege escalation in the Netmonitor component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Deeper analysisAI
CVE-2026-2780 is a privilege escalation vulnerability in the Netmonitor component affecting Mozilla Firefox, Firefox ESR, and Thunderbird. The issue, associated with CWE-269 (Improper Privilege Management) and lacking specific NVD CWE details, was assigned a critical CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). It was publicly disclosed on February 24, 2026, and addressed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Remote attackers require no privileges or user interaction to exploit this vulnerability over the network with low complexity. Successful exploitation enables high-impact confidentiality, integrity, and availability violations, allowing attackers to escalate privileges within affected applications, potentially leading to full compromise of the user's system.
Mozilla's security advisories (MFSA 2026-13, 15, 16, and 17) and the associated Bugzilla entry (ID 2007829) confirm the vulnerability's resolution through patches in the specified versions. Security practitioners should prioritize updating to Firefox 148 or later, Firefox ESR 140.8 or later, Thunderbird 148 or later, and Thunderbird 140.8 or later to mitigate this risk.
Details
- CWE(s)