CVE-2026-2802
Published: 24 February 2026
Summary
CVE-2026-2802 is a medium-severity Race Condition (CWE-362) vulnerability in Mozilla Firefox. Its CVSS base score is 4.2 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 3.7th 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 SC-18 (Mobile Code).
Deeper analysis
CVE-2026-2802 is a race condition vulnerability (CWE-362) in the JavaScript Garbage Collector (GC) component of Mozilla Firefox and Thunderbird. It affects versions prior to Firefox 148 and Thunderbird 148, where the flaw allows concurrent access issues during garbage collection operations in JavaScript execution. The vulnerability has a CVSS v3.1 base score of 4.2 (AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N), rated as Medium severity due to its network accessibility but high attack complexity and requirement for user interaction.
An unauthenticated remote attacker can exploit this vulnerability by crafting malicious web content that triggers the race condition in the JavaScript GC, typically requiring the user to interact with a malicious webpage or link. Successful exploitation could result in limited impacts, such as low-level disclosure of sensitive information or minor modification of data, without affecting availability or escalating privileges.
Mozilla's security advisories (MFSA 2026-13 and MFSA 2026-16) and the associated Bugzilla entry (bug 2011069) confirm the issue was addressed in Firefox 148 and Thunderbird 148. Security practitioners should prioritize updating affected browsers to these patched versions to mitigate the risk, as no workarounds are detailed in the provided references.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8454
Vulnerability details
Race condition in the JavaScript: GC component. This vulnerability was fixed in Firefox 148 and Thunderbird 148.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability enables drive-by exploitation of browser via malicious web content requiring user interaction (T1189, T1204.001) and direct client-side exploitation for limited info disclosure/data modification (T1203).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely installation of vendor patches that remediate the JavaScript GC race condition in Firefox/Thunderbird <148.
Restricts or monitors execution of mobile code (JavaScript) that an attacker must deliver to trigger the GC flaw.
Malicious-code protections on endpoints can block or sandbox web content crafted to exploit the browser GC race.