CVE-2026-8950

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: HTTP component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS Scores

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Meta Information

Published

2026-05-19

Last Modified

2026-05-20

Generated

2026-06-30

AI Q&A

2026-05-19

EPSS Evaluated

2026-06-28

NVD

CVE-2026-8950

EUVD

EUVD-2026-30898

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 151.0.0 (exc)
mozilla	firefox	to 140.11.0 (exc)
mozilla	thunderbird	to 140.11 (exc)
mozilla	thunderbird	to 151.0.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-346	The product does not properly verify that the source of data or communication is valid.

Attack-Flow Graph

Executive Summary

CVE-2026-8950 is a security vulnerability in the Networking: HTTP component of Mozilla Firefox and Firefox ESR. It involves a same-origin policy bypass, which means that the usual security restrictions that prevent one website from accessing data or resources from another website are circumvented. This vulnerability was fixed in Firefox 151 and Firefox ESR 140.11.

Compliance Impact

CVE-2026-8950 involves a same-origin policy bypass in Firefox's Networking: HTTP component, which could allow malicious websites to bypass security restrictions and potentially access sensitive data or interact with other sites without authorization.

Such unauthorized access to sensitive data could have implications for compliance with data protection standards and regulations like GDPR and HIPAA, which require strict controls over personal and sensitive information to prevent unauthorized disclosure.

However, the provided information does not explicitly state the direct impact of this vulnerability on compliance with these standards.

Impact Analysis

This vulnerability could allow malicious websites to bypass security restrictions imposed by the same-origin policy. As a result, attackers might gain unauthorized access to sensitive data or interact with other websites on behalf of the user, potentially leading to data theft or other malicious activities.

Mitigation Strategies

To mitigate this vulnerability, you should update your Firefox browser to version 151 or later, or Firefox ESR to version 140.11 or later, where the issue has been fixed.

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