CVE-2025-10859: Data stored in cookies for non-HTML content while browsing Incognito could be viewed after closing private tabs

Published Sep 28, 2025
·
Updated

Cookie storage for non-HTML temporary documents was being shared incorrectly with normal browsing content, allowing information from private tabs to escape Incognito mode even after the user closed all tabs

Affected Software

4 affected components
Mozilla Firefox for iOS<143.1
All of the following
Mozilla Firefox=143.1
Apple iOS
Mozilla Firefox Iphone Os<143.1.0

Event History

Sep 28, 2025
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Sep 30, 2025
CVE Published
via MITRE·12:49 PM
Data Sourced
via MITRE·12:49 PM
Description
Data Sourced
via NVD·01:15 PM
DescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

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Frequently Asked Questions

1

What is the severity of CVE-2025-10859?

CVE-2025-10859 has a severity rating of medium as it allows information to escape from private browsing.

2

How do I fix CVE-2025-10859?

To fix CVE-2025-10859, update Mozilla Firefox for iOS or Firefox to version 143.1 or later.

3

What is the impact of CVE-2025-10859?

CVE-2025-10859 allows cookie storage for non-HTML temporary documents to be improperly shared, risking user privacy.

4

Which versions are affected by CVE-2025-10859?

CVE-2025-10859 affects Mozilla Firefox for iOS versions prior to 143.1 and Firefox version 143.1 on iOS.

5

Can CVE-2025-10859 affect user data security?

Yes, CVE-2025-10859 can compromise user data security by allowing private browsing data to be accessed outside of Incognito mode.

Company

Resources

Contact

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