Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
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 LSA Secrets (T1003.004); ranked in the top 45% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
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 Data
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 Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.2.6
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds integer overflow defects before deployment.
Input validation directly requires checking for unexpected or malformed conditions before they propagate.
Secure engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer overflow during calculation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-754, a class-level weakness. Rules are authored against its narrower children: CWE-354.