Cyber Resilience

CVE-2026-8390

High

Published: 12 May 2026

Published
12 May 2026
Modified
14 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 0.0002 4.3th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-8390 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 Drive-by Compromise (T1189); ranked at the 4.3th 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 JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.0.3.

CWE(s)
CWE-416

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1189 Drive-by Compromise Initial Access
Adversaries may gain access to a system through a user visiting a website over the normal course of browsing.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
Why these techniques?

Use-after-free in browser JS/WebAssembly engine directly enables RCE via malicious web content, facilitating drive-by compromise and client exploitation.

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

CVEs Like This One

CVE-2026-4723Same product: Mozilla Firefox
CVE-2026-4691Same product: Mozilla Firefox
CVE-2026-4711Same product: Mozilla Firefox
CVE-2026-24869Same product: Mozilla Firefox
CVE-2026-4696Same product: Mozilla Firefox
CVE-2026-4725Same product: Mozilla Firefox
CVE-2026-3847Same product: Mozilla Firefox
CVE-2026-4701Same product: Mozilla Firefox
CVE-2026-4688Same product: Mozilla Firefox
CVE-2026-4684Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 150.0.3

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