Cyber Resilience

CVE-2026-4715

Mozilla Firefox ≤ 140.9.0

Published
24 March 2026
Modified
13 April 2026
Patch / advisory
CVSS Score v3.1 9.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS Score 0.0043 36th percentile
Risk Priority 67 floored blend · peak EPSS

Summary

CVE-2026-4715 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 36th 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-2026-4715 is an uninitialized memory vulnerability (CWE-908) in the Graphics: Canvas2D component of Mozilla products. It affects Firefox versions prior to 149, Firefox ESR versions prior to 140.9, Thunderbird versions prior to 149, and Thunderbird versions prior to 140.9. The vulnerability was publicly disclosed on 2026-03-24 and carries a CVSS v3.1 base score of 9.1, indicating critical severity.

Remote attackers can exploit this vulnerability over the network with low complexity, requiring no privileges, no user interaction, and without changing the scope of impact. Successful exploitation enables high confidentiality and availability impacts, such as unauthorized disclosure of sensitive information from uninitialized memory or denial-of-service via crashes, without affecting integrity.

Mozilla security advisories (MFSA 2026-20, 22, 23, 24) and the associated Bugzilla entry (bug 2018405) detail the patch, recommending immediate updates to Firefox 149, Firefox ESR 140.9, Thunderbird 149, or Thunderbird 140.9 to mitigate the issue. No workarounds are specified in the provided references.

EU & UK References

Vulnerability Data

Uninitialized memory in the Graphics: Canvas2D 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

T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
T1552 Unsecured Credentials Credential Access
Adversaries may search compromised systems to find and obtain insecurely stored credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-2794Same product: Mozilla Firefox
CVE-2024-3862Same product: Mozilla Firefox
CVE-2026-4716Same product: Mozilla Firefox
CVE-2026-16386Same product: Mozilla Firefox
CVE-2025-1942Same product: Mozilla Firefox
CVE-2026-16384Same product: Mozilla Firefox
CVE-2026-16385Same product: Mozilla Firefox
CVE-2023-32213Same product: Mozilla Firefox
CVE-2024-7526Same product: Mozilla Firefox
CVE-2026-2806Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 140.9.0 · ≤ 149.0

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.

PR.PS-06 mostly match
prevents

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.

finds

Security testing in development and acceptance can detect uninitialized resource usage through dynamic analysis and fuzzing.

prevents

Secure development life cycle mandates initialization checks and static analysis that can catch uninitialized resource use.

prevents

Application security requirements can specify mandatory initialization of variables and resources before use.

prevents

Secure system architecture and engineering principles include defensive coding practices that prevent use of uninitialized memory or objects.

prevents

Secure coding standards directly require explicit initialization of all variables and resources, substantially mitigating CWE-908.

References