CVE-2026-8971
Same-origin policy bypass in Firefox
Publication date: 2026-05-19
Last updated on: 2026-05-20
Assigner: Mozilla Corporation
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mozilla | firefox | to 151.0.0 (exc) |
| mozilla | thunderbird | to 151.0.0 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-346 | The product does not properly verify that the source of data or communication is valid. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
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.
How can this vulnerability impact me? :
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.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, update Firefox to version 151 or later where the issue has been fixed.