Cyber Posture

CVE-2026-8390

High

Published: 12 May 2026

Published
12 May 2026
Modified
13 May 2026
KEV Added
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Patch
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CVSS Score 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 5.1th 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 (inferred from references). Its CVSS base score is 7.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 5.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

Threat & Defense at a Glance

What attackers do: exploitation maps to Drive-by Compromise (T1189) and 1 other technique.
Threat & Defense Details

Likely Mitigating ControlsAI

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.

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

NVD Description

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.0.3.

Deeper analysisAI

Automated synthesis unavailable for this CVE.

Details

CWE(s)
CWE-416

Affected Products

Mozilla
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inferred from references and description; NVD did not file a CPE for this CVE

References