Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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-2026-2796 is a critical-severity Type Confusion (CWE-843) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Junk Data (T1001.001); ranked in the top 49% 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 SA-8 (Security and Privacy Engineering Principles) — 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-2026-2796 is a JIT miscompilation vulnerability in the JavaScript: WebAssembly component of Mozilla Firefox and Thunderbird. This flaw, classified under CWE-843 (incorrect type conversion or cast), allows for improper handling during just-in-time compilation of WebAssembly code, potentially leading to exploitable memory corruption. It affects versions of Firefox and Thunderbird prior to 148 and carries a CVSS v3.1 base score of 9.8, indicating critical severity due to its high impact on confidentiality, integrity, and availability.
A remote attacker can exploit this vulnerability over the network with low attack complexity, requiring no privileges, user interaction, or scope changes. By crafting malicious WebAssembly content deliverable via a website or other network-accessible vector, the attacker could trigger the miscompilation, enabling arbitrary code execution within the browser's sandboxed JavaScript engine. Successful exploitation would grant high-impact control over the affected process, potentially compromising the victim's system if chained with sandbox escapes.
Mozilla addressed this issue in Firefox 148 and Thunderbird 148, as detailed in security advisories MFSA 2026-13 and MFSA 2026-16, along with the upstream bug report at Bugzilla ID 2013165. Security practitioners should prioritize updating affected browsers to these patched versions and monitor for similar JIT-related issues in WebAssembly implementations.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8449
Vulnerability Data
JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 148 and Thunderbird 148.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.5.2V15.3.5
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and type-aware analysis) directly finds type-confusion flaws before deployment.
Engineering principles can require use of type-safe languages, static typing, and runtime type checks that structurally avoid allocating one type and accessing another.
Memory-protection controls limit the blast radius when a type-confusion access occurs but do not stop the flaw itself.
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 type-confusion flaws via safe typing, static analysis, and code review while the control itself addresses many additional 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.