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Mozilla Firefox CVE-2026-12322

| EUVDEUVD-2026-37068 MEDIUM
Improper Restriction of Rendered UI Layers or Frames (CWE-1021)
2026-06-16 mozilla GHSA-fm4m-52gr-mp53
XSS Mozilla
Medium
Disputed · 5.4 Vendor: mozilla
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Severity by source

Sources disagree (Low–Critical)
Vendor (mozilla) PRIMARY
5.4 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L
vuln.today AI
5.4 MEDIUM

Clickjacking (CWE-1021) canonically produces integrity impact via unintended user actions; I:N in source vector conflicts with the CWE; no availability impact expected for a UI-layer deception flaw.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
SUSE
CRITICAL
qualitative
Red Hat
3.4 LOW
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
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
Low

Lifecycle Timeline

3
Analysis Generated
Jul 23, 2026 - 16:40 vuln.today
CVE Published
Jun 16, 2026 - 11:52 cve.org
UNKNOWN (no severity yet)
CVE Published
Jun 16, 2026 - 11:52 cve.org
MEDIUM 5.4

DescriptionCVE.org

Clickjacking issue in the Widget: Gtk component. This vulnerability was fixed in Firefox 152.

AnalysisAI

Clickjacking via the Widget: Gtk component in Mozilla Firefox allows a remote, unauthenticated attacker to deceive users on Linux desktop systems into unintended interactions with improperly restricted GTK-rendered browser UI layers. All Firefox versions prior to 152 on GTK-based Linux platforms are affected, with fixes confirmed in Mozilla Foundation Security Advisories MFSA2026-57 and MFSA2026-60. No public exploit is identified at time of analysis; SSVC rates exploitation as 'none' and EPSS sits at 0.17% (6th percentile), indicating negligible active exploitation pressure despite the network-accessible attack vector.

Technical ContextAI

GTK (GIMP Toolkit) is the widget toolkit Firefox uses to render its user interface on Linux and Unix-based systems running X11 or Wayland display servers. CWE-1021 (Improper Restriction of Rendered UI Layers or Frames) identifies the root-cause class: the GTK widget component fails to adequately isolate or restrict overlapping rendered UI layers, permitting a crafted web page to visually spoof or overlay browser UI elements and deceive user interaction. This is a platform-specific defect - only Firefox builds that use the GTK backend are affected, as confirmed by CPE string cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* scoped to Linux deployments. The explicit tagging by SUSE and Red Hat corroborates downstream exposure on major enterprise Linux distributions that ship GTK-based Firefox packages. Two separate MFSAs reference this fix (MFSA2026-57 and MFSA2026-60), suggesting the patch was applied to both the standard and Extended Support Release (ESR) Firefox tracks.

RemediationAI

The primary fix is upgrading to Firefox 152 or later, as confirmed by Mozilla advisories MFSA2026-57 (https://www.mozilla.org/security/advisories/mfsa2026-57/) and MFSA2026-60 (https://www.mozilla.org/security/advisories/mfsa2026-60/). Users on Red Hat Enterprise Linux or CentOS should apply updates via 'dnf update firefox'; SUSE users should use 'zypper update MozillaFirefox'. Given the low EPSS and SSVC exploitation-none designation, this vulnerability can be addressed within standard patching cycles rather than emergency response timelines. If immediate patching is infeasible, a compensating control is to enforce URL allowlisting via browser enterprise policies or a proxy filter, restricting access to known-trusted sites and thereby eliminating attacker delivery of the malicious page required for exploitation - the trade-off being reduced user browsing freedom. Disabling GTK-specific overlay rendering is not an available browser configuration option without source-level modification and is not a practical control.

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
openSUSE Tumbleweed Fixed
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

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CVE-2026-12322 vulnerability details – vuln.today
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