CVE-2026-53899: Vulnerability in Mozilla Firefox for iOS
CVE-2026-53899 is a vulnerability in Firefox for iOS where partial domain matching was used when attaching cookies to PDF requests. This flaw allowed a malicious site on a suffix domain to receive cookies belonging to the target site, potentially leaking sensitive cookie data. The issue was fixed in Firefox for iOS version 152.0. The vendor advisory classifies the impact as high. No CVSS score is provided.
AI Analysis
Technical Summary
Firefox for iOS improperly used partial domain matching when attaching cookies to PDF requests, which enabled a malicious site on a suffix domain to access cookies intended for the target site. This cross-origin cookie leakage vulnerability was addressed and fixed in Firefox for iOS 152.0. The Mozilla advisory confirms the vulnerability and its resolution, emphasizing the high impact due to potential cookie leakage.
Potential Impact
The vulnerability allows a malicious site on a suffix domain to receive cookies belonging to a different target site, leading to cross-origin cookie leakage. This can compromise user privacy and session integrity by exposing sensitive cookie data to unauthorized domains. The vendor rates the impact as high.
Mitigation Recommendations
A fix is available in Firefox for iOS version 152.0. Users and administrators should update to this version to remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-53899: Vulnerability in Mozilla Firefox for iOS
Description
CVE-2026-53899 is a vulnerability in Firefox for iOS where partial domain matching was used when attaching cookies to PDF requests. This flaw allowed a malicious site on a suffix domain to receive cookies belonging to the target site, potentially leaking sensitive cookie data. The issue was fixed in Firefox for iOS version 152.0. The vendor advisory classifies the impact as high. No CVSS score is provided.
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Firefox for iOS improperly used partial domain matching when attaching cookies to PDF requests, which enabled a malicious site on a suffix domain to access cookies intended for the target site. This cross-origin cookie leakage vulnerability was addressed and fixed in Firefox for iOS 152.0. The Mozilla advisory confirms the vulnerability and its resolution, emphasizing the high impact due to potential cookie leakage.
Potential Impact
The vulnerability allows a malicious site on a suffix domain to receive cookies belonging to a different target site, leading to cross-origin cookie leakage. This can compromise user privacy and session integrity by exposing sensitive cookie data to unauthorized domains. The vendor rates the impact as high.
Mitigation Recommendations
A fix is available in Firefox for iOS version 152.0. Users and administrators should update to this version to remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-06-11T06:20:46.257Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-56/","vendor":"Mozilla"}]
Threat ID: 6a314c870b89be6888b4cf55
Added to database: 6/16/2026, 1:15:51 PM
Last enriched: 6/16/2026, 1:30:58 PM
Last updated: 6/17/2026, 4:57:33 AM
Views: 10
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