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Mozilla Firefox CVE-2026-16398

| EUVDEUVD-2026-46236 HIGH
Information Exposure (CWE-200)
2026-07-21 mozilla GHSA-jpp9-98p6-wx73
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
7.5 HIGH

Remote web content triggers the leak without auth or interaction (AV:N/AC:L/PR:N/UI:N); impact is cross-origin data disclosure only, so C:H with I:N/A:N.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/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 - 19:05 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

Site isolation issue in the Graphics component. This vulnerability was fixed in Firefox 153.

AnalysisAI

Information disclosure in Mozilla Firefox before version 153 stems from a site isolation weakness in the Graphics component, allowing a remote attacker to read cross-origin data that should be siloed between sites. The confidentiality-only flaw (CVSS 7.5, C:H) is network-reachable without authentication or user interaction, but carries no public exploit and a low EPSS score (0.13%, 3rd percentile), indicating theoretical rather than active risk. It is not listed in CISA KEV; no public exploit identified at time of analysis.

Technical ContextAI

The issue lives in Firefox's Graphics subsystem and its interaction with the browser's site isolation (project Fission) security boundary. Site isolation is designed to render content from different origins in separate OS processes so that one site cannot read another site's memory or rendered content; a defect in how the Graphics component enforces this boundary can let data cross between origins. Classed as CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), the root cause is a failure to keep origin-scoped graphics/rendering data confined to its owning site context, which can leak information such as rendered pixels or memory contents belonging to another origin.

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 ships automatic updates, ensure background updates are enabled and restart the browser to apply the new build; managed environments should push 153 through their update/patch management tooling. No standalone workaround is documented for this Graphics/site-isolation flaw; if patching must be delayed, reduce exposure by having users avoid untrusted websites and confirm site isolation (Fission) is enabled, though these are partial measures and not substitutes for the update. Verify ESR channel guidance directly with Mozilla if ESR is in use, as ESR fix availability is not confirmed in the provided data.

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Same weakness CWE-200 – Information Exposure

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Same technique Information Disclosure

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CVE-2015-1701 HIGH POC
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CVE-2017-0147 HIGH POC
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CVE-2014-6324 HIGH POC
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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-2026-16398 vulnerability details – vuln.today
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