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Mozilla Firefox CVE-2026-74978

| EUVDEUVD-2026-60691 HIGH
Improper Restriction of Rendered UI Layers or Frames (CWE-1021)
2026-08-18 mozilla GHSA-v52q-fx4j-2fmf
XSS Mozilla
High
Disputed · 8.1 Vendor: mozilla
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Severity by source

Sources disagree (Low–High)
Vendor (mozilla) PRIMARY
8.1 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
vuln.today AI
8.1 HIGH

Network-delivered clickjacking requires no attacker privileges and only user interaction; high C/I reflects Widget's potential for sensitive browser action hijacking with no availability impact.

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

4
Analysis Generated
Aug 18, 2026 - 19:25 vuln.today
CVSS changed
Aug 18, 2026 - 19:22 NVD
8.1 (HIGH)
CVE Published
Aug 18, 2026 - 12:23 cve.org
HIGH 8.1
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Clickjacking issue in the Widget component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

AnalysisAI

Clickjacking in Mozilla Firefox's Widget component enables a remote unauthenticated attacker to trick users into triggering high-impact unintended browser actions through overlaid UI deception. All Firefox desktop releases prior to version 154 - and all ESR releases prior to 153.1 - are affected across platforms per CPE cpe:2.3:a:mozilla:firefox:*. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Attacker hosts malicious webpage with overlay
Delivery
Transparent layer positioned over Firefox Widget element
Exploit
User visits page and clicks apparent UI control
Execution
Click intercepted by hidden Widget target
Impact
Unintended high-impact browser action executed
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Vulnerability AssessmentAI

Exploitation The attacker must serve a malicious webpage to the target user, and the user must visit that page and perform at least one click interaction - consistent with the CVSS UI:R metric. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 8.1 High rating is driven by network delivery (AV:N), low complexity (AC:L), no required privileges (PR:N), and high confidentiality and integrity impact scores - unusual severity for a pure clickjacking flaw, suggesting the Widget component exposure can be leveraged for more than superficial click-hijacking and may enable sensitive browser actions or meaningful data exposure. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker hosts a malicious webpage containing a transparent iframe or overlay layer positioned precisely over a Firefox Widget element such as a permission dialog button or browser prompt. When a targeted user visits the page and clicks what appears to be a benign UI control, the click is silently captured by the hidden Widget target, potentially confirming a sensitive browser permission, initiating an unintended download, or completing a high-impact browser action. …
Remediation The vendor-released patch is Firefox 154 for the standard release channel and Firefox ESR 153.1 for the extended support channel; organizations should upgrade all Firefox desktop installations immediately via the browser's built-in update mechanism or enterprise deployment tooling. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: inventory Firefox deployments by version number and operating system to identify affected instances; notify end users of clickjacking risks and advise heightened caution with overlaid or unexpected UI elements. …

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
Container suse/kiosk/firefox-esr:140.14-75.12 Affected
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Desktop Applications 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Fixed

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CVE-2026-74978 vulnerability details – vuln.today
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