Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-16387

Severity CVSS v4.0:
Pending analysis
Type:
CWE-200 Information Leak / Disclosure
Publication date:
21/07/2026
Last modified:
24/07/2026

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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 9.80 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x
9.80
Severity 3.x
CRITICAL

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:* 140.13.0 (excluding)
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:* 153.0.0 (excluding)
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* 140.13.0 (excluding)
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* 141.0 (including) 153.0 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools