Skip to main content

Red Hat CVE-2026-4702

| EUVDEUVD-2026-14821 CRITICAL
Access of Resource Using Incompatible Type (Type Confusion) (CWE-843)
2026-03-24 mozilla GHSA-mrrg-439g-x65p
Information Disclosure Memory Corruption Red Hat Mozilla Suse
Critical
Disputed · 9.8 NVD
View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Deliver malicious JavaScript to Firefox browser
  2. Exploit
    JIT compiler miscompiles code
  3. Execution
    Bypass security checks
  4. Impact
    Execute arbitrary code with browser privileges

Vulnerability Assessment

Weakness
CWE
CWE-843
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Type safety enforcement
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Sign in to read
Exploitation Conditions

Remote unauthenticated attacker can exploit Firefox versions below 149 (or ESR below 140.9) by delivering crafted JavaScript code. No victim interaction required if malicious script executes automatically on visited webpage. Default Firefox configurations are vulnerable.
Impact

Without CVSS scores, EPSS probability data, or confirmed KEV/active exploitation status provided in the source data, assessment relies on structural factors. The vulnerability affects widely-deployed browsers (Firefox and Firefox ESR) across all versions below specified thresholds, which significantly increases potential impact scope. Information disclosure from JIT miscompilation typically requires specific JavaScript payloads to trigger, suggesting moderate attack complexity, though no POC availability was documented. The fact that Mozilla issued multiple security advisories (MFSA2026-20 and MFSA2026-22) indicates this was treated as a priority security issue. The vulnerability's presence in both standard Firefox and ESR (Extended Support Release) branches suggests widespread exposure. Real-world risk is elevated due to the prevalence of Firefox, the potential for remote exploitation via malicious websites, and the information disclosure impact which could compromise user privacy or enable further attacks. However, without active exploitation evidence or CVSS/EPSS data, this should be prioritized based on user base size and deployment patterns rather than assumed critical severity.
Exploit ScenarioDerived

An attacker could host a malicious webpage containing carefully crafted JavaScript code designed to trigger the JIT miscompilation. When a user visits this page in a vulnerable Firefox browser, the malicious script could exploit the miscompiled code path to read sensitive data from the browser's memory, such as authentication tokens, cached credentials, or data from other browser tabs. The attack requires user interaction (visiting the malicious site) but no special privileges, making it a viable vector for mass exploitation through drive-by attacks or watering hole campaigns.
Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.0% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Mar 24, 2026

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.

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.

Affected VersionsENISA

Firefox unspecified <149
Firefox ESR unspecified <140.9

Affected Packages

euvd firefox_esr_unspecified fix: 140.9
euvd firefox_unspecified fix: 149

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Sign in to check
Technical ContextAI · show details

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.

Know when Mozilla gets its next vulnerability

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources
Continue with Google Continue with GitHub

No credit card · 7-day full trial

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
Red Hat 6.1 MEDIUM

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

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
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.

Executive ViewAI

Why It Matters

Organizations using the JavaScript Engine component. This vulnerability affects Firefox face critical risk from CVE-2026-4702 rated CVSS 9.8. Successful exploitation could critically impact the confidentiality, integrity, and availability of affected systems. Organizations should apply vendor updates immediately when available and implement compensating controls in the interim.

Business Impact: Severe
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score
0.0%
Top 96% exploitable
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Out-of-Cycle
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
Very High
Technical Impact
Total

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Related Vulnerabilities in Firefox Multiple Memory and Boundary Vulnerabilities

View all 27
CVE-2026-4712 HIGH
7.5
CVE-2026-4714 HIGH
7.5
CVE-2026-4715 CRITICAL
9.1
CVE-2026-4717 CRITICAL
9.8
CVE-2026-4718 HIGH
8.1
CVE-2026-4719 HIGH
7.5
CVE-2026-4720 CRITICAL
9.8
CVE-2026-4726 HIGH
7.5
CVE-2026-4708 HIGH
7.5
CVE-2026-4713 HIGH
7.5
CVE-2026-4722 HIGH
8.8
CVE-2026-4693 HIGH
7.5
CVE-2026-4729 CRITICAL
9.8
CVE-2026-4695 HIGH
7.5
CVE-2026-4696 CRITICAL
9.8
CVE-2026-4697 HIGH
7.5
CVE-2026-4698 CRITICAL
9.8
CVE-2026-4700 CRITICAL
9.8
CVE-2026-4701 CRITICAL
9.8
CVE-2026-4704 HIGH
7.5
CVE-2026-4706 HIGH
7.5
CVE-2026-4707 HIGH
7.5
CVE-2026-4709 HIGH
7.5
CVE-2026-4710 CRITICAL
9.8
CVE-2026-4711 CRITICAL
9.8
CVE-2026-4723 CRITICAL
9.8

More in Mozilla

View all
CVE-2015-4495 HIGH POC
8.8 Aug 08

The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote
CVE-2013-1690 HIGH POC
8.8 Jun 26

Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before

CVE-2013-0758 CRITICAL POC
9.3 Jan 13

Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderb
CVE-2013-0753 CRITICAL POC
9.3 Jan 13

Use-after-free vulnerability in the serializeToStream implementation in the XMLSerializer component in Mozilla Firefox b
CVE-2012-3993 CRITICAL POC
9.3 Oct 10

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbi
CVE-2013-1710 CRITICAL POC
10.0 Aug 07

The crypto.generateCRMFRequest function in Mozilla Firefox before 23.0, Firefox ESR 17.x before 17.0.8, Thunderbird befo
CVE-2017-3823 HIGH POC
8.8 Feb 01

An issue was discovered in the Cisco WebEx Extension before 1.0.7 on Google Chrome, the ActiveTouch General Plugin Conta
CVE-2014-8636 HIGH POC
7.5 Jan 14

The XrayWrapper implementation in Mozilla Firefox before 35.0 and SeaMonkey before 2.32 does not properly interact with

CVE-2013-0757 CRITICAL POC
9.3 Jan 13

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.2, Thunderbi
CVE-2014-1510 CRITICAL POC
9.8 Mar 19

The Web IDL implementation in Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and Se
CVE-2014-1511 CRITICAL POC
9.8 Mar 19

Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and SeaMonkey before 2.25 allow remo
CVE-2013-0643 HIGH
8.8 Feb 27

The Firefox sandbox in Adobe Flash Player before 10.3.183.67 and 11.x before 11.6.602.171 on Windows and Mac OS X, and b

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

View all
CVE-2011-0611 HIGH POC
8.8
CVE-2012-0507 CRITICAL POC
9.8
CVE-2017-8291 HIGH POC
7.8
CVE-2016-7201 HIGH POC
8.8
CVE-2017-0037 HIGH POC
8.1
CVE-2019-0752 HIGH POC
7.5
CVE-2017-5070 HIGH POC
8.8
CVE-2023-3079 HIGH POC
8.8

Same technique Information Disclosure

View all
CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2025-68613 HIGH POC
8.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5

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

References

Advisories & patches
ADVISORY https://access.redhat.com/errata/RHSA-2026:5930 ADVISORY https://access.redhat.com/errata/RHSA-2026:5931 ADVISORY https://access.redhat.com/errata/RHSA-2026:5932 ADVISORY https://access.redhat.com/errata/RHSA-2026:6188 ADVISORY https://access.redhat.com/errata/RHSA-2026:6342 ADVISORY https://access.redhat.com/errata/RHSA-2026:6917 ADVISORY https://access.redhat.com/errata/RHSA-2026:7837 ADVISORY https://access.redhat.com/errata/RHSA-2026:7838 ADVISORY https://access.redhat.com/errata/RHSA-2026:7839 ADVISORY https://access.redhat.com/errata/RHSA-2026:7840 ADVISORY https://access.redhat.com/errata/RHSA-2026:7841 ADVISORY https://access.redhat.com/errata/RHSA-2026:7842 ADVISORY https://access.redhat.com/errata/RHSA-2026:7843 ADVISORY https://access.redhat.com/errata/RHSA-2026:7845 ADVISORY https://access.redhat.com/errata/RHSA-2026:7858 ADVISORY https://access.redhat.com/errata/RHSA-2026:8284 ADVISORY https://access.redhat.com/errata/RHSA-2026:8285 ADVISORY https://access.redhat.com/errata/RHSA-2026:8286 ADVISORY https://access.redhat.com/errata/RHSA-2026:8287 ADVISORY https://access.redhat.com/errata/RHSA-2026:8288 ADVISORY https://access.redhat.com/errata/RHSA-2026:8289 ADVISORY https://access.redhat.com/errata/RHSA-2026:8290 ADVISORY https://access.redhat.com/errata/RHSA-2026:8315 ADVISORY https://access.redhat.com/errata/RHSA-2026:8427 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-4702 ADVISORY https://vuldb.com/?id.352748 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1126/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1127/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1163/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:20978/ REF https://bugzilla.mozilla.org/show_bug.cgi?id=2013560 REF https://www.mozilla.org/security/advisories/mfsa2026-20/ REF https://www.mozilla.org/security/advisories/mfsa2026-22/ REF https://www.mozilla.org/security/advisories/mfsa2026-23/ REF https://www.mozilla.org/security/advisories/mfsa2026-24/

Search Externally

GitHub PoC Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy