CVE-2026-9309

MEDIUM 5.4

Arbitrary JavaScript execution in internal pages via Reader View JSON-LD injection

CVSS Score

5.4

EPSS Score

0.0%

EPSS Percentile

0th

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.

Vendor	mozilla
Product	firefox for ios
Ecosystems	Browser JavaScript
Industries	Technology
Published	Jun 1, 2026
Last Updated	Jun 1, 2026

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Affected Versions

Mozilla / Firefox for iOS

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

bugzilla.mozilla.org: https://bugzilla.mozilla.org/show_bug.cgi?id=2036573 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-53/

Credits

Muneaki Nishimura