CVE-2026-4695
Mozilla Firefox ≤ 140.9.0
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-2026-4695 is a high-severity Improper Check for Unusual or Exceptional Conditions (CWE-754) vulnerability in Mozilla Firefox. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked in the top 48% 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-2026-4695 is a vulnerability involving incorrect boundary conditions in the Audio/Video: Web Codecs component of Mozilla products. It affects Firefox, Firefox ESR, Thunderbird, and was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9. The issue is classified under CWE-754 (Improper Check for Unusual or Exceptional Conditions) with a CVSS v3.1 base score of 7.5.
The vulnerability can be exploited remotely 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). Successful exploitation results in high-impact denial of service (A:H) with no impact on confidentiality or integrity, potentially causing application crashes.
Mozilla security advisories, including MFSA 2026-20, 2026-22, 2026-23, and 2026-24, along with Bugzilla entry 2020030, detail the patch deployments in the specified versions, recommending users update to these releases for mitigation.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-14810
Vulnerability Data
Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 149, 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
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation explicitly exercises unusual conditions to find missing or incorrect checks.
Input validation directly requires checking for unexpected or malformed conditions before they propagate.
Security engineering principles include structured handling of edge cases and exceptions during design.
Memory-protection mechanisms limit the exploitability of an overflow that results from an incorrect size calculation.
Flaw-remediation processes that include vulnerability scanning or static analysis will surface buffer-size errors.
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 prevent buffer-size miscalculations via coding standards, reviews, and testing, while fixing this single weakness only partially fulfills the broader control.
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.