CVE-2026-2757
Published: 24 February 2026
Summary
CVE-2026-2757 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 Exploitation for Client Execution (T1203); ranked at the 38.6th 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-2026-2757 is a high-severity vulnerability stemming from incorrect boundary conditions in the WebRTC Audio/Video 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 issue is cataloged under CWE-1384 with an additional NVD-CWE-noinfo mapping and carries a CVSS v3.1 base score of 9.8.
The vulnerability enables exploitation over the network (AV:N) with low attack complexity (AC:L), requiring no privileges (PR:N) or user interaction (UI:N), and without changing scope (S:U). Remote attackers can thus achieve high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H), potentially leading to full system compromise such as arbitrary code execution via malicious WebRTC traffic.
Mozilla's security advisories (MFSA 2026-13 through 2026-16) and the associated Bugzilla entry (bug 2001637) detail the fix applied in the listed versions. Security practitioners should prioritize updating affected Firefox and Thunderbird installations to the patched releases to mitigate the risk.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8478
Vulnerability details
Incorrect boundary conditions in the WebRTC: Audio/Video 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 unauthenticated RCE via malicious WebRTC traffic in client applications (Firefox/Thunderbird) directly enables client-side exploitation for code execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-2 directly mandates timely remediation of known flaws like CVE-2026-2757 by applying patches to vulnerable Firefox and Thunderbird versions, preventing remote code execution.
RA-5 requires vulnerability scanning to identify systems running affected Firefox and Thunderbird versions prior to the patched releases.
SI-5 ensures monitoring of vendor security advisories such as Mozilla's MFSA 2026-13 through 2026-16 to promptly learn of and address CVE-2026-2757.