CVE-2026-74962
Undergoing Analysis Undergoing Analysis - In Progress

Site Isolation Bypass in Firefox via Cookies Component

Vulnerability report for CVE-2026-74962, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: Mozilla Corporation

Description

Site isolation issue in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, and Firefox ESR 153.1.

CVSS Scores

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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
EUVD

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
mozilla firefox 154
mozilla firefox esr
mozilla firefox_esr 140.14
mozilla firefox_esr 153.1
mozilla firefox to 154 (inc)
mozilla firefox_esr to 140.14 (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

Attack-Flow Graph

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Executive Summary

This is a site isolation issue in Firefox's Networking: Cookies component. Site isolation is a security feature that separates content from different websites to prevent malicious sites from accessing data from other sites. A flaw in this component could allow unauthorized access or manipulation of cookies across different sites.

Detection Guidance

This vulnerability is specific to Firefox versions before 154, Firefox ESR 140.14, and Firefox ESR 153.1. Detection involves checking installed Firefox versions. Use commands like 'firefox --version' or check package managers (e.g., 'apt list --installed | grep firefox' for Debian/Ubuntu). If versions are below the fixed releases, the system is vulnerable.

Impact Analysis

If exploited, this vulnerability could allow an attacker to steal or manipulate cookies from other websites, potentially leading to session hijacking, unauthorized account access, or exposure of sensitive data stored in cookies.

Compliance Impact

This vulnerability could lead to unauthorized access to personal data, which may violate GDPR's data protection requirements or HIPAA's safeguards for protected health information. Organizations using affected Firefox versions may face compliance risks if exploited.

Mitigation Strategies

Update Firefox to version 154 or later, Firefox ESR 140.14 or later, or Firefox ESR 153.1 or later to address the site isolation issue in the Networking: Cookies component.

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