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Mozilla EUVDEUVD-2026-14821

| CVE-2026-4702 CRITICAL
Access of Resource Using Incompatible Type (Type Confusion) (CWE-843)
2026-03-24 mozilla GHSA-mrrg-439g-x65p
Mozilla Memory Corruption Information Disclosure Red Hat Suse
Critical
Disputed · 9.8 NVD
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Severity by source

Sources disagree (Medium–Critical)
NVD PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SUSE
CRITICAL
qualitative
Red Hat
6.1 MEDIUM
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 VectorNVD

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

Lifecycle Timeline

4
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
EUVD ID Assigned
Mar 24, 2026 - 12:45 euvd
EUVD-2026-14821
Analysis Generated
Mar 24, 2026 - 12:45 vuln.today
CVE Published
Mar 24, 2026 - 12:30 nvd
CRITICAL 9.8

DescriptionCVE.org

JIT miscompilation in the JavaScript Engine component. This vulnerability affects Firefox < 149 and Firefox ESR < 140.9.

AnalysisAI

A JIT (Just-In-Time) compilation miscompilation vulnerability exists in Firefox's JavaScript Engine that can lead to information disclosure. This affects Firefox versions below 149 and Firefox ESR versions below 140.9. An attacker can exploit this vulnerability through malicious JavaScript code to potentially disclose sensitive information from the browser's memory or process space.

Technical ContextAI

The vulnerability resides in the JavaScript Engine component of Mozilla Firefox, specifically in the JIT compiler which translates JavaScript bytecode into native machine code for performance optimization. The affected products are identified via CPE strings cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* and cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*, indicating all versions of both Firefox and Firefox ESR up to the patched releases are potentially vulnerable. JIT miscompilation occurs when the compiler incorrectly optimizes code, potentially causing unintended memory access or state leakage. While a specific CWE was not provided in the vulnerability data, JIT miscompilation issues typically fall under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) or related memory safety categories. The vulnerability's classification as an information disclosure issue suggests the miscompilation allows reading memory that should be restricted from access.

RemediationAI

Upgrade Firefox to version 149 or later, and Firefox ESR to version 140.9 or later immediately. Users should navigate to Help > About Firefox (or Help > About Firefox ESR) which will automatically download and prompt installation of the latest patched version. Organizations managing Firefox deployments should use Mozilla's official security advisories at https://www.mozilla.org/security/advisories/mfsa2026-20/ and https://www.mozilla.org/security/advisories/mfsa2026-22/ to coordinate patching across their environments. Until patching is completed, users should avoid visiting untrusted websites and consider disabling JavaScript in high-risk scenarios, though this significantly impacts web functionality. Additionally, keeping Firefox and Firefox ESR updated with automatic security updates enabled is the primary control to prevent exploitation of JIT miscompilation vulnerabilities.

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Same weakness CWE-843 – Access of Resource Using Incompatible Type (Type Confusion)

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Same technique Memory Corruption

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7.8

Vendor StatusVendor

Debian

firefox
Release Status Fixed Version Urgency
sid vulnerable 148.0.2-1 -
(unstable) fixed (unfixed) -
firefox-esr
Release Status Fixed Version Urgency
bullseye vulnerable 115.14.0esr-1~deb11u1 -
bullseye (security) vulnerable 140.8.0esr-1~deb11u1 -
bookworm vulnerable 128.14.0esr-1~deb12u1 -
bookworm (security) vulnerable 140.8.0esr-1~deb12u1 -
trixie (security), trixie vulnerable 140.8.0esr-1~deb13u1 -
forky, sid vulnerable 140.8.0esr-1 -
(unstable) fixed (unfixed) -

SUSE

Severity: Critical
Product Status
Image SLES15-SP5-SAP-Azure-LI-BYOS Image SLES15-SP5-SAP-Azure-LI-BYOS-Production Image SLES15-SP5-SAP-Azure-VLI-BYOS Image SLES15-SP5-SAP-Azure-VLI-BYOS-Production Image SLES15-SP6-SAP-Azure-LI-BYOS Image SLES15-SP6-SAP-Azure-LI-BYOS-Production Image SLES15-SP6-SAP-Azure-VLI-BYOS Image SLES15-SP6-SAP-Azure-VLI-BYOS-Production Image SLES15-SP7-SAP-Azure-LI-BYOS-Production Image SLES15-SP7-SAP-Azure-VLI-BYOS-Production Affected
SUSE Liberty Linux 10 Fixed
SUSE Liberty Linux 8 Fixed
SUSE Liberty Linux 9 Fixed
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed

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EUVD-2026-14821 vulnerability details – vuln.today
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