Firefox DOM Navigation Site Isolation Vulnerability
CVE-2026-16399 Published on July 21, 2026

Site isolation issue in the DOM: Navigation component
Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

NVD

Vulnerability Analysis

CVE-2026-16399 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Type

Origin Validation Error

The software does not properly verify that the source of data or communication is valid.


Products Associated with CVE-2026-16399

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Mozilla Firefox
 
Mozilla Thunderbird
 

Affected Versions

Mozilla Firefox: Mozilla Thunderbird:

Exploit Probability

EPSS
0.15%
Percentile
4.56%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.