CVE-2026-53899: Mozilla Firefox Mobile

Medium severity, CVSS 6.5. EPSS: 0.1% chance of exploitation in the next 30 days.

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.

Affected products

• Mozilla Firefox Mobile: before 152.0 (fixed in 152.0)

Published 2026-06-16. Last modified 2026-06-17.