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CVE-2026-9309

Medium

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.

SeverityMedium
CVSS5.4
Exploit probability—
ProductMozilla Firefox
PublishedJun 1, 2026
First seenJun 1, 2026
Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

Update
  • mozilla firefox151.2 or later

Affected products

ProductAffected versionsFixed in
mozilla firefoxv < 151.2151.2

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