CVE-2026-53899

Severity CVSS v4.0:

Pending analysis

Type:

CWE-345 Insufficient Verification of Data Authenticity

Publication date:

16/06/2026

Last modified:

16/06/2026

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.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 6.50 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): Low
Integrity (I): Low
Availability (A): None

Base Score 3.x

6.50

Severity 3.x

MEDIUM

References to Advisories, Solutions, and Tools

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