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Mozilla Firefox CVE-2026-74938

| EUVDEUVD-2026-60676 CRITICAL
Protection Mechanism Failure (CWE-693)
2026-08-18 mozilla GHSA-g352-92jc-35rp
Authentication Bypass Mozilla Red Hat Suse
9.1
CVSS 3.1 · Vendor: mozilla
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Severity by source

Vendor (mozilla) PRIMARY
9.1 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
vuln.today AI
8.1 HIGH

Remote web content over the network with no privileges, but a victim must load a malicious page so UI:R rather than UI:N; high confidentiality/integrity impact via the browser content process, 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
7.5 HIGH
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Red Hat
7.5 HIGH
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:H/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

3
Analysis Generated
Aug 18, 2026 - 20:27 vuln.today
CVE Published
Aug 18, 2026 - 12:23 cve.org
CRITICAL 9.1
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Mitigation bypass in the JavaScript: GC component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

Articles & Coverage 1

News Critical Protection Mechanism Bypass in Mozilla Firefox GC - CVE-2026-74938 Aug 18, 2026

AnalysisAI

Protection-mechanism bypass in the Firefox JavaScript engine's garbage collector (JavaScript: GC) undermines a built-in exploit mitigation, weakening a defense that normally hinders memory-corruption exploitation. The flaw affects Mozilla Firefox and Firefox ESR and was addressed by the vendor in Firefox 154 and Firefox ESR 153.1. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Lure user to malicious site
Delivery
Deliver crafted JavaScript payload
Exploit
Bypass GC exploit mitigation
Execution
Chain with memory-corruption primitive
Impact
Execute code / disclose memory in content process
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Vulnerability AssessmentAI

Exploitation Exploitation targets the Firefox JavaScript engine's garbage collector, so the concrete prerequisite is that the victim renders attacker-controlled JavaScript - i.e. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The provided CVSS 3.1 base score is 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N), which on paper describes a remote, unauthenticated, no-interaction attack with high confidentiality and integrity impact. … 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 JavaScript that abuses the GC mitigation bypass, then lures a Firefox user to visit it (via phishing link, malvertising, or a compromised site). The bypass neutralizes a memory-safety hardening measure, and when combined with a memory-corruption primitive it can lead to disclosure of sensitive process memory or code execution in the browser content process. …
Remediation Vendor-released patch: upgrade to Firefox 154 or Firefox ESR 153.1 or later, which contain the fix. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours, inventory all Firefox and Firefox ESR deployments across your organization and validate that update channels are configured correctly. …

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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-2026-74938 vulnerability details – vuln.today
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