Medium severity · published Jun 16, 2026
CVE-2026-53899
Cross-origin cookies could be leaked when opening a PDF link
6.5
CVSS
0.1%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 1% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FM
Firefox Mobile · Mozilla
before 152.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53899
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-53899
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=2042909
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-56/
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