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Mozilla Firefox CVE-2026-74934

| EUVDEUVD-2026-60743 HIGH
Information Exposure (CWE-200)
2026-08-18 mozilla GHSA-fwhj-g32m-x3vf
Information Disclosure Mozilla
7.5
CVSS 3.1 · Vendor: mozilla
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Severity by source

Vendor (mozilla) PRIMARY
7.5 HIGH
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI
6.1 MEDIUM

Site isolation bypass inherently crosses origin boundaries warranting S:C; CWE-200 description supports only C:H impact; I:H and A:H from the provided vector are not supported by information-disclosure framing.

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

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

4
Analysis Generated
Aug 21, 2026 - 21:25 vuln.today
CVSS changed
Aug 21, 2026 - 21:22 NVD
7.5 (HIGH)
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

Site isolation issue in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.

AnalysisAI

Site isolation bypass in Firefox's Graphics: CanvasWebGL component allows a malicious web page to leak cross-origin data through the browser's graphics subsystem. All Firefox releases prior to version 154 are affected, along with ESR branches fixed in 115.39, 140.14, and 153.1. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Attacker crafts malicious WebGL canvas page
Delivery
Victim visits page via phishing or malvertising
Exploit
WebGL rendering triggers site isolation boundary flaw
Execution
Cross-origin data exposed to attacker page context
Impact
Sensitive session or page content exfiltrated to attacker
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Vulnerability AssessmentAI

Exploitation Exploitation requires the victim to visit a malicious web page, satisfying the UI:R requirement in the CVSS vector. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The provided CVSS 3.1 vector (AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H, score 7.5) reflects meaningful impact, but the real-world risk is moderated by several factors. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker hosts a malicious web page containing crafted WebGL canvas content engineered to trigger the site isolation boundary flaw. When a user visits the page - potentially delivered via phishing or a malicious advertisement - the WebGL operation causes the browser to expose data from a cross-origin context, such as content loaded in a co-located banking or webmail tab. …
Remediation Standard channel users should upgrade to Firefox 154 or later. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours, notify security and IT teams of the vulnerability and prepare interim guidance restricting Firefox usage in high-risk environments with sensitive cross-origin access; establish monitoring for announced patch releases (Firefox 154, ESR 115.39, 140.14, and 153.1). …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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Same weakness CWE-200 – Information Exposure

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Same technique Information Disclosure

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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-2026-74934 vulnerability details – vuln.today
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