CVE-2026-100809
Received Received - Intake

Same-origin policy bypass in Firefox

Publication date: 2026-09-29

Last updated on: 2026-09-29

Assigner: Mozilla Corporation

Description
Same-origin policy bypass in the DevTools component. This vulnerability was fixed in Firefox ESR 153.4 and Firefox 157.

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Meta Information

Published
2026-09-29
Last Modified
2026-09-29
Generated
2026-09-29
AI Q&A
2026-09-29
EPSS Evaluated
N/A
NVD
CVE-2026-100809
EUVD
EUVD-2026-88788

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
mozilla firefox to 153.4 (inc)
mozilla firefox to 157 (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 DevTools component. The same-origin policy is a security feature that prevents scripts from one website from accessing data on another website. A bypass here could allow malicious scripts to access sensitive data across different origins.

Impact Analysis

If exploited, this vulnerability could allow attackers to steal sensitive data from other websites you visit while using Firefox. It may also enable unauthorized actions on your behalf on other sites, leading to potential account takeovers or data breaches.

Compliance Impact

This vulnerability could lead to unauthorized access to personal data, violating GDPR's data protection principles and HIPAA's safeguards for protected health information. Organizations using affected Firefox versions may face compliance violations and legal penalties.

Mitigation Strategies

Update Firefox ESR to version 153.4 or later and Firefox to version 157 or later to address the same-origin policy bypass in DevTools.

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