CVE-2026-4694
Published: 24 March 2026
Summary
CVE-2026-4694 is a high-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Mozilla Firefox. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked in the top 48.8% of CVEs by exploit likelihood; 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 RA-5 (Vulnerability Monitoring and Scanning).
Deeper analysis
CVE-2026-4694 is an integer overflow vulnerability stemming from incorrect boundary conditions in the Graphics component of Mozilla Firefox and Thunderbird. It affects versions of Firefox prior to 149, Firefox ESR prior to 115.34 and 140.9, and Thunderbird prior to 149 and 140.9. The issue is classified under CWE-190 (Integer Overflow or Wraparound) and CWE-754 (Improper Check for Unusual or Exceptional Conditions), with a CVSS v3.1 base score of 7.5.
The vulnerability enables remote attackers to exploit it over a network with low complexity, requiring no privileges, user interaction, or authentication. Successful exploitation results in high-impact denial of service, such as application crashes or resource exhaustion, without affecting confidentiality or integrity (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Mozilla's security advisories (MFSA 2026-20 through 2026-23) and the associated Bugzilla entry (bug 2018430) confirm the fix was implemented in the listed versions. Security practitioners should ensure affected systems are updated to Firefox 149 or later, Firefox ESR 115.34/140.9 or later, and Thunderbird 149/140.9 or later to mitigate the issue.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-14809
Vulnerability details
Incorrect boundary conditions, integer overflow in the Graphics component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Integer overflow in browser graphics component enables remote exploitation causing application crash/resource exhaustion (CWE-190), directly matching T1499.004 Application or System Exploitation for Endpoint Denial of Service.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely identification, reporting, and patching of software flaws like this integer overflow in Firefox and Thunderbird graphics component.
Enables ongoing vulnerability scanning to identify systems running affected versions of Firefox or Thunderbird vulnerable to this CVE.
Mandates obtaining and acting on vendor security advisories like Mozilla's MFSA to address this specific vulnerability through updates.
Hardening callouts derived
Configuration rules from DISA STIG baselines that reduce the attack surface for weaknesses of the type cited by this CVE. Derived transitively via CVE→CWE→STIG over `controls_xwalks` (authoritative rows only).
Oracle Linux 8 (3 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. via CWE-754
- V-248573 The OL 8 file integrity tool must notify the system administrator (SA) when changes to the baseline configuration or anomalies in the operation of any security functions are discovered within an organizationally defined frequency. via CWE-754
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. via CWE-754
Oracle Linux 9 (1 rule)
- V-271452 OL 9 must use a Linux Security Module configured to enforce limits on system services. via CWE-754