CVE-2026-16387

CRITICAL

Mozilla Firefox - Site Isolation Issue in the Networking Component

Title source: rule
STIX 2.1

Description

Site isolation issue in the Networking component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

References (5)

Core 5

Scores

CVSS v3 9.8
EPSS 0.0020
EPSS Percentile 10.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact total

Details

CWE
CWE-200 CWE-284 CWE-346
Status published
Products (7)
mozilla/firefox < 140.13.0
mozilla/firefox < 153.0.0
Mozilla/Firefox 140.13 - 140.*
Mozilla/Firefox 153
mozilla/thunderbird < 140.13.0
Mozilla/Thunderbird 140.13 - 140.*
Mozilla/Thunderbird 153
Published Jul 21, 2026
Tracked Since Jul 21, 2026