CVE-2026-8971
Analyzed Analyzed - Analysis Complete
Same-origin policy bypass in Firefox

Publication date: 2026-05-19

Last updated on: 2026-05-20

Assigner: Mozilla Corporation

Description
Same-origin policy bypass in the Networking: JAR component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.
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Meta Information
Published
2026-05-19
Last Modified
2026-05-20
Generated
2026-06-10
AI Q&A
2026-05-19
EPSS Evaluated
2026-06-08
NVD
CVE-2026-8971
EUVD
EUVD-2026-30919
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
mozilla firefox to 151.0.0 (exc)
mozilla thunderbird to 151.0.0 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-346 The product does not properly verify that the source of data or communication is valid.
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Mitigation Strategies

To mitigate this vulnerability, update Firefox to version 151 or later where the issue has been fixed.

Executive Summary

This vulnerability is a same-origin policy bypass in the Networking: JAR component of Firefox. The same-origin policy is a security measure that restricts how documents or scripts loaded from one origin can interact with resources from another origin. A bypass means that this restriction can be circumvented, potentially allowing unauthorized access to data or functionality across different origins. This issue was fixed in Firefox version 151.

Impact Analysis

By bypassing the same-origin policy in the JAR networking component, an attacker could potentially access or manipulate data from other origins without proper authorization. This could lead to unauthorized data exposure, cross-site scripting, or other security breaches when using affected versions of Firefox prior to version 151.

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