CVE-2026-74938

Analyzed Analyzed - Analysis Complete

Mitigation Bypass in Firefox JavaScript GC Component

Publication date: 2026-08-18

Last updated on: 2026-08-19

Assigner: Mozilla Corporation

Description

Mitigation bypass in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-18

Last Modified

2026-08-19

Generated

2026-09-07

AI Q&A

2026-08-18

EPSS Evaluated

2026-09-06

NVD

CVE-2026-74938

EUVD

EUVD-2026-60676

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 154.0.0 (exc)
mozilla	thunderbird	to 154.0 (exc)
mozilla	firefox	to 153.1.0 (exc)
mozilla	thunderbird	to 153.1.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-693	The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

Attack-Flow Graph

Executive Summary

This vulnerability is a mitigation bypass in the JavaScript garbage collection component of Firefox. It allows attackers to bypass security measures, potentially leading to arbitrary code execution or other malicious activities.

Detection Guidance

This vulnerability is specific to Firefox and Thunderbird versions before 154 (or ESR 153.1). Detection involves checking installed versions of these applications. Use commands like 'firefox --version' or 'thunderbird --version' to verify if your system is affected.

Impact Analysis

If exploited, this vulnerability could allow attackers to run malicious code on your system, steal sensitive data, or perform actions as if they were you. Users of affected Firefox versions are at risk until they update to Firefox 154 or Firefox ESR 153.1.

Compliance Impact

The vulnerability allows unauthorized code execution or data access due to a mitigation bypass in JavaScript GC, which could lead to data breaches or unauthorized access to sensitive information. This may impact compliance with GDPR (data protection) and HIPAA (health data privacy) by increasing the risk of unauthorized data exposure or processing.

Mitigation Strategies

Update Firefox to version 154 or later and Firefox ESR to version 153.1 or later to address the mitigation bypass in the JavaScript: GC component.

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