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Mozilla Firefox CVE-2026-74958

| EUVDEUVD-2026-60684 HIGH
Improper Restriction of Rendered UI Layers or Frames (CWE-1021)
2026-08-18 mozilla GHSA-hr33-3v76-m7gj
Information Disclosure XSS Mozilla Red Hat Suse
7.5
CVSS 3.1 · Vendor: mozilla
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Severity by source

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

CWE-1021 (UI layer restriction) implies a user must be exposed to a deceptive rendered interface element, making UI:R more consistent with the root cause than the vendor-assigned UI: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
HIGH
qualitative
Red Hat
6.1 MEDIUM
qualitative

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

3
Analysis Generated
Aug 18, 2026 - 20:26 vuln.today
CVE Published
Aug 18, 2026 - 12:23 cve.org
HIGH 7.5
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Information disclosure in the WebRTC component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

AnalysisAI

Information disclosure via the WebRTC component in Mozilla Firefox allows network-accessible attackers to exfiltrate sensitive browser data due to improper restriction of rendered UI layers (CWE-1021). All Firefox releases prior to version 154 and all Firefox ESR releases prior to version 153.1 are affected across all platforms listed under CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Attacker hosts crafted webpage with malicious WebRTC and UI layer payload
Delivery
Victim Firefox user visits page via phishing, redirect, or malvertising
Exploit
WebRTC component initializes and CWE-1021 UI layer bypass triggers
Execution
Sensitive browser or network data disclosed to attacker origin
Impact
Attacker collects exfiltrated information
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Vulnerability AssessmentAI

Exploitation The target must be running Mozilla Firefox prior to version 154 (standard channel) or Firefox ESR prior to version 153.1, and must visit or be redirected to a malicious or compromised web page under attacker control. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The vendor-supplied CVSS vector of AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N scores 7.5, indicating a high-severity, fully network-accessible, unauthenticated disclosure with no complexity barrier. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker hosts a malicious webpage containing crafted WebRTC session setup code combined with improperly restricted UI layer elements that exploit the CWE-1021 flaw to read sensitive data across frame boundaries or from the WebRTC context. A Firefox user who visits the page - through a phishing link, malvertising redirect, or compromised third-party site - triggers the WebRTC component, which leaks confidential data (such as local IP addresses, media device identifiers, or session tokens) to the attacker-controlled origin. …
Remediation The primary remediation is to upgrade to Mozilla Firefox 154 or later for users on the standard release channel, or to Firefox ESR 153.1 or later for enterprise deployments using the Extended Support Release. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours, catalog Firefox deployments organization-wide and flag systems handling sensitive data as high-priority. …

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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-2026-74958 vulnerability details – vuln.today
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