Cyber Resilience

CVE-2026-8947

High

Published: 19 May 2026

Published
19 May 2026
Modified
19 May 2026
KEV Added
—
Patch
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CVSS Score v3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
EPSS Score 0.0037 28.5th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-8947 is a high-severity Use After Free (CWE-416) vulnerability in Mozilla Firefox. Its CVSS base score is 7.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 28.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Use-after-free in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CWE(s)
CWE-416

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1059.007 JavaScript Execution
Adversaries may abuse various implementations of JavaScript for execution.
attack.mitre.org →
Why these techniques?

Use-after-free in browser DOM bindings enables client-side code execution via malicious JavaScript.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v18.1

CVEs Like This One

CVE-2026-0884Same product: Mozilla Firefox
CVE-2026-2789Same product: Mozilla Firefox
CVE-2026-2787Same product: Mozilla Firefox
CVE-2026-2765Same product: Mozilla Firefox
CVE-2026-2763Same product: Mozilla Firefox
CVE-2026-2767Same product: Mozilla Firefox
CVE-2026-8090Same product: Mozilla Firefox
CVE-2026-2758Same product: Mozilla Firefox
CVE-2025-1010Same product: Mozilla Firefox
CVE-2026-2786Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 115.36.0 · ≤ 151.0.0 · 140.0 — 140.11.0
mozilla
thunderbird
≤ 140.11

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

References