CVE-2026-53899

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

State: Published
Severity: 6.5 Medium
Published: Jun 16, 2026
Updated: Jun 16, 2026
Reserved: Jun 11, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N	CISA-ADP

Weaknesses

CWE-345 Insufficient Verification of Data Authenticity

Affected Products

Product	Versions
Firefox for iOSMozilla	152.0 and laterNot affected

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2042909
https://www.mozilla.org/security/advisories/mfsa2026-56/

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