Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-6749 is a high-severity Use of Uninitialized Resource (CWE-908) vulnerability in Mozilla Firefox. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Steganography (T1001.002); ranked at the 48th 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-2026-6749 is an information disclosure vulnerability caused by uninitialized memory in the Graphics: Canvas2D component of Mozilla Firefox and Thunderbird. Classified under CWE-908, it received a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) and was published on 2026-04-21. The flaw affects versions of Firefox prior to 150, Firefox ESR prior to 115.35 and 140.10, Thunderbird prior to 150, and Thunderbird prior to 140.10.
Remote attackers can exploit this vulnerability over the network with low attack complexity, without requiring user privileges or interaction. Exploitation enables high-impact confidentiality violations by leaking contents of uninitialized memory through the Canvas2D interface, potentially exposing sensitive data rendered or processed in the browser.
Mozilla's security advisories MFSA 2026-30, MFSA 2026-31, MFSA 2026-32, and MFSA 2026-33, along with Bugzilla entry 2022610, document the issue and confirm fixes in the specified versions. Mitigation requires updating to Firefox 150, Firefox ESR 115.35 or 140.10, Thunderbird 150, or Thunderbird 140.10.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-24090
Vulnerability Data
Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
- 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.