CVE-2026-74963
Undergoing Analysis Undergoing Analysis - In Progress

Same-Origin Policy Bypass in Firefox

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: Mozilla Corporation

Description
Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, 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-2026-74963
EUVD
EUVD-2026-60661

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
mozilla firefox to 154 (inc)
mozilla firefox_esr to 140.14 (inc)
mozilla firefox_esr to 153.1 (inc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a same-origin policy bypass in Firefox's Networking: Cookies component. The same-origin policy is a security feature that prevents scripts from one website from accessing data from another website. A bypass means attackers could potentially access cookies or other sensitive data from different origins, violating expected security boundaries.

Detection Guidance

Detection requires checking Firefox and Firefox ESR versions. Run 'firefox --version' or 'firefox-esr --version' to verify if versions are below Firefox 154 or Firefox ESR 140.14/153.1.

Impact Analysis

If exploited, this vulnerability could allow attackers to steal cookies or session tokens from other websites, leading to unauthorized access to user accounts. It may also enable cross-site request forgery (CSRF) attacks or expose sensitive data stored in cookies, compromising user privacy and security.

Compliance Impact

This vulnerability could lead to unauthorized data access, violating GDPR's principles of data protection and user consent. For HIPAA, it may compromise protected health information if session tokens or cookies contain such data. Organizations using affected Firefox versions could face compliance violations and legal penalties.

Mitigation Strategies

Update Firefox to version 154 or later and Firefox ESR to 140.14 or 153.1 or newer. Disable automatic updates temporarily if needed until patches are applied.

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