CVE-2026-9309
Analyzed Analyzed - Analysis Complete
Firefox for iOS Reader View HTML Injection Leads to XSS

Publication date: 2026-06-01

Last updated on: 2026-06-03

Assigner: Mozilla Corporation

Description
Firefox for iOS Reader View did not properly escape HTML tags in JSON-LD metadata. A malicious page could inject markup that changed Reader View behavior and leaked sensitive URL parameters. These parameters could then be used to access internal pages, potentially resulting in arbitrary JavaScript execution in an internal origin. This vulnerability was fixed in Firefox for iOS 151.2.
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Meta Information
Published
2026-06-01
Last Modified
2026-06-03
Generated
2026-06-21
AI Q&A
2026-06-01
EPSS Evaluated
2026-06-20
NVD
CVE-2026-9309
EUVD
EUVD-2026-33630
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
mozilla firefox to 151.2 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
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Executive Summary

This vulnerability in Firefox for iOS Reader View occurs because HTML tags in JSON-LD metadata were not properly escaped.

A malicious webpage could exploit this flaw by injecting markup that changes how Reader View behaves and causes sensitive URL parameters to be leaked.

These leaked parameters could then be used to access internal pages and potentially allow arbitrary JavaScript execution within an internal origin.

Impact Analysis

The impact of this vulnerability includes the exposure of sensitive URL parameters which could lead to unauthorized access to internal pages.

Additionally, it could enable an attacker to execute arbitrary JavaScript code within an internal origin, potentially compromising the security and integrity of the application.

Compliance Impact

The provided information does not specify how this vulnerability affects compliance with common standards and regulations such as GDPR or HIPAA.

Mitigation Strategies

To mitigate this vulnerability, update Firefox for iOS to version 151.2 or later, where the issue with improper HTML tag escaping in JSON-LD metadata within Reader View has been fixed.

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