CVE-2026-53899
Undergoing Analysis Undergoing Analysis - In Progress

Firefox for iOS Cookie Exposure via Partial Domain Matching in PDF Requests

Publication date: 2026-06-16

Last updated on: 2026-06-16

Assigner: Mozilla Corporation

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.

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Meta Information

Published
2026-06-16
Last Modified
2026-06-16
Generated
2026-07-06
AI Q&A
2026-06-16
EPSS Evaluated
2026-07-05
NVD
CVE-2026-53899
EUVD
EUVD-2026-37077

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
mozilla firefox_for_ios 152.0

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-345 The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.

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Executive Summary

This vulnerability in Firefox for iOS involves the browser using partial domain matching when attaching cookies to PDF requests. Because of this, a malicious website on a suffix domain can receive cookies that belong to a different target site. Essentially, cookies intended for one domain could be leaked to another, potentially exposing sensitive user session data.

Impact Analysis

The vulnerability can lead to cross-origin cookie leakage, allowing a malicious site to intercept cookies meant for another site. This could expose sensitive user session information, potentially enabling unauthorized access to user accounts or personal data.

Compliance Impact

This vulnerability allows a malicious site on a suffix domain to receive cookies belonging to a target site, potentially exposing sensitive user session data across unrelated domains.

Such exposure of sensitive user data could lead to non-compliance with data protection regulations like GDPR and HIPAA, which require strict controls on personal and sensitive information to prevent unauthorized access or leakage.

Mitigation Strategies

To mitigate this vulnerability, you should update Firefox for iOS to version 152.0 or later, where the issue has been fixed.

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