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Mozilla Firefox CVE-2026-16400

| EUVDEUVD-2026-46238 HIGH
Information Exposure (CWE-200)
2026-07-21 mozilla GHSA-573v-jgf3-jx4p
Information Disclosure Red Hat Mozilla
High
Disputed · 7.5 Vendor: mozilla
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Severity by source

Sources disagree (Medium–Critical)
Vendor (mozilla) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
vuln.today AI
6.5 MEDIUM

Network-delivered web content with no privileges, but exploitation realistically requires the victim to load a malicious page (UI:R); impact is confidentiality-only, so I:N/A:N.

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

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

4
Analysis Generated
Jul 22, 2026 - 19:06 vuln.today
CVSS changed
Jul 22, 2026 - 18:22 NVD
7.5 (HIGH)
CVE Published
Jul 21, 2026 - 12:38 cve.org
UNKNOWN (no severity yet)
CVE Published
Jul 21, 2026 - 12:38 cve.org
HIGH 7.5

DescriptionCVE.org

Information disclosure in the DOM: Security component. This vulnerability was fixed in Firefox 153.

AnalysisAI

Information disclosure in Mozilla Firefox's DOM: Security component allows remote attackers to read sensitive cross-origin or in-process data via crafted web content, undermining the browser's same-origin and security boundary enforcement. Any Firefox version prior to 153 is affected, and exploitation is remote and unauthenticated with no user interaction beyond visiting a malicious page. The issue was reported and fixed by Mozilla; no public exploit identified at time of analysis and EPSS exploitation probability is low (0.13%).

Technical ContextAI

The flaw resides in Firefox's 'DOM: Security' subsystem, the layer responsible for enforcing web security invariants such as the same-origin policy, Content Security Policy, and isolation between documents within the Document Object Model. Rooted in CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), the vulnerability class typically stems from a boundary that should prevent one origin or context from observing another's data failing to do so - for example leaking cross-origin content, memory contents, or restricted attributes into a context the attacker controls. The affected product per CPE is cpe:2.3:a:mozilla:firefox (all versions before the fix), covering the mainline desktop browser.

RemediationAI

Vendor-released patch: Firefox 153 - upgrade all Firefox installations to version 153 or later, which is the primary and complete fix per Mozilla advisory MFSA2026-68 (https://www.mozilla.org/security/advisories/mfsa2026-68/). Because Firefox auto-updates by default, ensure the update channel is not disabled and force a restart to apply the new build across managed endpoints; in enterprise environments push the update via your software distribution or Firefox ESR/policy channel. No specific pre-patch workaround is published for this DOM: Security disclosure; as an interim compensating control you can restrict browsing to trusted sites via network filtering or a browsing policy and avoid untrusted web content, accepting the usability trade-off, until the upgrade is deployed. Reference the Bugzilla entry (https://bugzilla.mozilla.org/show_bug.cgi?id=2050430) for technical detail once it becomes public.

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Same weakness CWE-200 – Information Exposure

View all
CVE-2024-24919 HIGH POC
8.6
CVE-2016-6415 HIGH POC
7.5
CVE-2013-7331 MEDIUM POC
6.5
CVE-2025-31125 MEDIUM POC
5.3
CVE-2025-11749 CRITICAL POC
9.8
CVE-2017-16894 HIGH POC
7.5
CVE-2017-11165 CRITICAL POC
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CVE-2020-3259 HIGH
7.5

Same technique Information Disclosure

View all
CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5
CVE-2014-6324 HIGH POC
8.8

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-2026-16400 vulnerability details – vuln.today
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