CVE-2026-74986
Undergoing Analysis Undergoing Analysis - In Progress

Firefox 154 CSS Parsing Component Site Isolation Issue

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: Mozilla Corporation

Description
Site isolation issue in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

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Meta Information

Published
2026-08-18
Last Modified
2026-08-18
Generated
2026-08-18
AI Q&A
2026-08-18
EPSS Evaluated
N/A
NVD
CVE-2026-74986
EUVD
EUVD-2026-60698

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
mozilla firefox 154
mozilla firefox_esr 153.1
mozilla firefox to 154 (inc)
mozilla firefox_esr to 153.1 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a site isolation issue in the CSS Parsing and Computation component of Firefox. It allows potential cross-site data leaks due to improper separation of content from different sites during CSS processing.

Impact Analysis

An attacker could exploit this to access sensitive data from other websites you visit, such as login credentials or personal information, if you use a vulnerable version of Firefox.

Compliance Impact

This vulnerability could lead to unauthorized data exposure, potentially violating GDPR's data protection requirements or HIPAA's safeguards for protected health information if exploited.

Mitigation Strategies

Update Firefox to version 154 or later and Firefox ESR to version 153.1 or later to address the CSS Parsing and Computation component vulnerability.

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