CVE-2026-4716
Mozilla Firefox ≤ 140.9.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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-2026-4716 is a critical-severity Use of Uninitialized Resource (CWE-908) vulnerability in Mozilla Firefox. Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique OS Credential Dumping (T1003); ranked at the 33th percentile by exploit likelihood (below the median); 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 SA-15 (Development Process, Standards, and Tools) — 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-2026-4716 is a high-severity vulnerability involving incorrect boundary conditions and uninitialized memory in the JavaScript Engine component. It affects Mozilla Firefox versions prior to 149, Firefox ESR prior to 140.9, Thunderbird prior to 149, and Thunderbird prior to 140.9. The issue, classified under CWE-908 (Use of Uninitialized Resource), received a CVSS v3.1 base score of 9.1, reflecting its critical nature due to network accessibility, low attack complexity, and no requirements for privileges or user interaction.
A remote attacker can exploit this vulnerability over the network without authentication or user interaction. Successful exploitation enables high-impact confidentiality violations, such as disclosure of sensitive memory contents, and high-impact availability disruptions, potentially leading to denial-of-service conditions like application crashes, all within the unchanged security scope.
Mozilla addressed the vulnerability in the specified fixed releases: Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9. Security advisories, including MFSA2026-20, MFSA2026-22, MFSA2026-23, and MFSA2026-24, along with Bugzilla entry 2018592, detail the patches and recommend immediate updates to mitigate the risk.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-14848
Vulnerability Data
Incorrect boundary conditions, uninitialized memory in the JavaScript Engine 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 (including static analysis) can find uses of uninitialized resources after they are coded.
Requiring documented development standards and tools can mandate initialization checks and safe patterns that stop the weakness from being introduced.
Engineering principles can require explicit resource initialization before use, structurally avoiding uninitialized access.
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 activities such as static analysis and code review directly prevent use of uninitialized resources while also addressing many other weaknesses.
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.