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Mozilla Firefox CVE-2026-16366

| EUVDEUVD-2026-46197 HIGH
Improper Privilege Management (CWE-269)
2026-07-21 mozilla GHSA-2h4f-4mx5-4hwr
Privilege Escalation Red Hat Mozilla
8.8
CVSS 3.1 · Vendor: mozilla
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Severity by source

Vendor (mozilla) PRIMARY
8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI
8.8 HIGH

Browser DOM flaw is network-reachable and low-complexity, but realistically requires the victim to load attacker content, so UI:R rather than the vendor's UI:N; high C/I/A reflect privilege escalation.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
CRITICAL
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

7
Re-analysis Queued
Jul 24, 2026 - 21:22 vuln.today
cvss_changed
Severity Changed
Jul 24, 2026 - 21:22 NVD
CRITICAL HIGH
CVSS changed
Jul 24, 2026 - 21:22 NVD
9.8 (CRITICAL) 8.8 (HIGH)
Analysis Generated
Jul 22, 2026 - 17:10 vuln.today
CVSS changed
Jul 22, 2026 - 16:22 NVD
9.8 (CRITICAL)
CVE Published
Jul 21, 2026 - 12:37 cve.org
UNKNOWN (no severity yet)
CVE Published
Jul 21, 2026 - 12:37 cve.org
CRITICAL 9.8

DescriptionCVE.org

Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 153.

AnalysisAI

Privilege escalation in Mozilla Firefox's DOM Navigation component (fixed in Firefox 153) allows an attacker to improperly gain elevated privileges within the browser, per Mozilla advisory MFSA2026-68. The flaw carries a CVSS 9.8 rating claiming full confidentiality, integrity, and availability impact with no privileges or user interaction, though this is atypical for a browser DOM bug. There is no public exploit identified at time of analysis, and EPSS exploitation probability is low (0.14%, 4th percentile).

Technical ContextAI

The vulnerability lives in Firefox's DOM Navigation component, the subsystem that governs how documents are loaded, history is managed, and origins transition during page navigation (aligned with the WHATWG HTML Navigation and Navigation API surface). The root cause is classified as CWE-269 (Improper Privilege Management), meaning the component fails to correctly enforce or assign privilege boundaries - in a browser context this typically manifests as content-level JavaScript or a web document acquiring privileges it should not have, such as chrome/parent-process capabilities or cross-origin authority. The single affected CPE is cpe:2.3:a:mozilla:firefox, indicating the desktop Firefox application rather than a specific OS component.

RemediationAI

Vendor-released patch: Firefox 153 - upgrade all Firefox installations to version 153 or later, which is the primary and complete fix per MFSA2026-68 (https://www.mozilla.org/security/advisories/mfsa2026-68/). Because Firefox auto-updates by default, ensure automatic updates are enabled and not blocked by enterprise policy, and force a restart to apply the update. Where immediate patching is not possible, compensating controls are limited for a DOM-level flaw but can reduce exposure: restrict browsing to trusted sites via policy/allowlisting, disable or tighten JavaScript on untrusted origins (trade-off: breaks most modern web apps), and deploy web/DNS filtering to block access to unknown malicious pages (trade-off: incomplete coverage against novel URLs). For managed fleets, use Firefox ESR/enterprise policies to enforce the updated build.

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Same weakness CWE-269 – Improper Privilege Management

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Same technique Privilege Escalation

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Desktop Applications 15 SP7 Affected
SUSE Linux Enterprise Module for Package Hub 15 SP7 Affected

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CVE-2026-16366 vulnerability details – vuln.today
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