CVE-2026-53900: Cookie injection was possible when opening a PDF link

Published Jun 16, 2026
·
Updated

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.

Affected Software

3 affected components
All of the following
Mozilla Firefox=152
Apple iOS
Mozilla Firefox Mobile Iphone Os<152.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade Firefox for iOS to a version that resolves this vulnerability.

    Fixed in 152.0

Event History

Jun 16, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
CVE Published
via MITRE·11:53 AM
Data Sourced
via MITRE·11:53 AM
Description
Data Sourced
via NVD·01:16 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-2026-53900?

The severity of CVE-2026-53900 is classified as medium with a CVSS score of 4.3.

2

How do I fix CVE-2026-53900?

To fix CVE-2026-53900, users should update to the latest version of Mozilla Firefox for iOS.

3

What is the impact of CVE-2026-53900?

CVE-2026-53900 allows a malicious site to inject arbitrary cookies into requests to an unrelated target domain.

4

Which software is affected by CVE-2026-53900?

CVE-2026-53900 affects Mozilla Firefox on iOS and Firefox Mobile on iPhone OS.

5

When was CVE-2026-53900 published?

CVE-2026-53900 was published on June 16, 2026.

Company

Resources

Contact

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