CVE-2026-8391

Vulnerability

Overview

CVE-2026-8391 is an unspecified issue in the JavaScript Engine component of Firefox, reported by researcher ggwhyp. The vulnerability was addressed in Firefox 150.0.3, as part of the Mozilla Foundation Security Advisory 2026-45 [1]. While the exact nature of the bug is not publicly detailed, Mozilla classified its impact as high, suggesting it could lead to severe consequences such as arbitrary code execution or browser crashes.

Exploitation

Context

Given that the vulnerability resides in the JavaScript Engine, exploitation likely requires an attacker to craft a malicious web page or script that triggers the flaw when processed by the browser. No authentication or special network position is needed beyond standard web access. The lack of public technical details means the specific attack vector remains undisclosed, but typical JavaScript Engine vulnerabilities are exploitable through crafted JavaScript code.

Impact

Assessment

Mozilla's advisory rates the impact as high, indicating that successful exploitation could allow an attacker to execute arbitrary code in the context of the browser, potentially leading to full system compromise. Alternatively, the issue might cause a denial of service through a crash. The CVSS v3 score of 5.3 (Medium) reflects a moderate severity, but the advisory's high impact rating underscores the seriousness of the flaw.

Mitigation

Status

The vulnerability is patched in Firefox 150.0.3. Users are strongly advised to update their browsers to the latest version to mitigate the risk. No workarounds have been provided, and the bug report (Bug 2038575) is currently restricted [2].