CVE-2026-9309: Vulnerability in Mozilla Firefox for iOS
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.
AI Analysis
Technical Summary
Firefox for iOS Reader View failed to properly escape HTML tags in JSON-LD metadata, enabling a malicious page to inject markup that modifies Reader View behavior and leaks sensitive URL parameters. These leaked parameters could be exploited to access internal pages and achieve arbitrary JavaScript execution in an internal origin. The vulnerability was addressed and fixed in Firefox for iOS 151.2 as per Mozilla's security advisory MFSA2026-53.
Potential Impact
The vulnerability allows an attacker to inject arbitrary JavaScript in an internal origin by exploiting improper escaping in JSON-LD metadata within Reader View. This can lead to leakage of sensitive URL parameters and unauthorized access to internal pages, posing a high security risk to users of Firefox for iOS prior to version 151.2.
Mitigation Recommendations
This vulnerability is fixed in Firefox for iOS version 151.2. Users and administrators should update to this version or later to remediate the issue. No additional mitigation is required as the vendor has provided an official fix.
CVE-2026-9309: Vulnerability in Mozilla Firefox for iOS
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.
CVSS v3.1
Score 5.4medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Firefox for iOS Reader View failed to properly escape HTML tags in JSON-LD metadata, enabling a malicious page to inject markup that modifies Reader View behavior and leaks sensitive URL parameters. These leaked parameters could be exploited to access internal pages and achieve arbitrary JavaScript execution in an internal origin. The vulnerability was addressed and fixed in Firefox for iOS 151.2 as per Mozilla's security advisory MFSA2026-53.
Potential Impact
The vulnerability allows an attacker to inject arbitrary JavaScript in an internal origin by exploiting improper escaping in JSON-LD metadata within Reader View. This can lead to leakage of sensitive URL parameters and unauthorized access to internal pages, posing a high security risk to users of Firefox for iOS prior to version 151.2.
Mitigation Recommendations
This vulnerability is fixed in Firefox for iOS version 151.2. Users and administrators should update to this version or later to remediate the issue. No additional mitigation is required as the vendor has provided an official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-05-22T18:16:52.497Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-53/","vendor":"Mozilla"}]
Threat ID: 6a1d832ee29bf47b50f6aa42
Added to database: 6/1/2026, 1:03:42 PM
Last enriched: 6/1/2026, 1:33:37 PM
Last updated: 6/2/2026, 5:03:05 AM
Views: 7
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