CVE-2026-53899

MEDIUM 6.5

Cross-origin cookies could be leaked when opening a PDF link

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

Firefox for iOS used partial domain matching when attaching cookies to PDF requests, allowing a malicious site on a suffix domain to receive cookies belonging to the target site. This vulnerability was fixed in Firefox for iOS 152.0.

Vendor	mozilla
Product	firefox for ios
Ecosystems	Browser JavaScript
Industries	Technology
Published	Jun 16, 2026
Last Updated	Jun 16, 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=2042909 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-56/

Credits

Muneaki Nishimura