Medium severity · published Jun 16, 2026
CVE-2026-53900
Cookie injection was possible when opening a PDF link
4.3
CVSS
0.1%
EPSS
No
On KEV
Description
Firefox for iOS preserved cookies set on the initial PDF request across cross-origin HTTP redirects in TemporaryDocument, allowing a malicious site to inject arbitrary cookies into requests to an unrelated target domain. This vulnerability was fixed in Firefox for iOS 152.0.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
None
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-2026-53900
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-53900
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=2043204
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-56/
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