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Firefox Esr CVE-2026-4690

| EUVDEUVD-2026-14804 HIGH
Integer Overflow or Wraparound (CWE-190)
2026-03-24 mozilla GHSA-r7ww-hwqf-cqr6
Buffer Overflow Integer Overflow Mozilla Firefox Esr
8.6
CVSS 3.1 · NVD
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Attack ChainAIDerived

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

  1. Access
    Deliver malicious web content
  2. Exploit
    Trigger integer overflow in XPCOM component
  3. Execution
    Escape browser sandbox
  4. Impact
    Crash or disable Firefox process

Vulnerability Assessment

Weakness
CWE
CWE-190
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Integer overflow checks
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.

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Exploitation Conditions

Remote unauthenticated attacker can exploit this against Firefox versions < 149, Firefox ESR < 115.34, and Firefox ESR < 140.9. No special configuration required. The vulnerability exists in the default XPCOM component with no user interaction needed.
Impact

This vulnerability presents a critical real-world risk despite missing CVSS and EPSS scores in the public data. The sandbox escape nature indicates a high-impact technical vulnerability that directly violates the trust boundary between untrusted web content and the host system, suggesting a CVSS score likely in the 8.0-9.8 range with network attack vector and low attack complexity. The fact that Mozilla issued three separate security advisories (MFSA2026-20, MFSA2026-21, MFSA2026-22) across different Firefox product lines indicates coordinated disclosure across multiple affected versions, typical of actively exploited or imminent exploitation scenarios. Without explicit KEV or POC confirmation in the provided data, the sandbox escape classification and multi-branch patch deployment suggest high exploitation probability; SSVC analysis would likely rate this as Automatable (memory safety issue in widely-deployed component) with Technical Impact of complete system compromise. Organizations should prioritize patching immediately rather than waiting for EPSS scores or exploit confirmation.
Exploit ScenarioDerived

An attacker hosts a malicious webpage containing specially crafted JavaScript that triggers the integer overflow condition in Firefox's XPCOM component during a routine DOM operation or extension interaction. When a user visits the compromised website with a vulnerable Firefox version, the overflow bypasses the sandbox boundary check, granting the attacker access to the file system, system memory, and potentially the ability to execute native code with the same privileges as the Firefox process. Depending on browser privilege separation on the target system, this could lead to credential theft, malware installation, or lateral movement to other system components.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 24, 2026

A sandbox escape vulnerability exists in Mozilla Firefox due to incorrect boundary conditions and integer overflow within the XPCOM component, allowing attackers to break out of the browser's security sandbox and potentially execute arbitrary code with elevated privileges. Firefox versions below 149, Firefox ESR below 115.34, and Firefox ESR below 140.9 are affected. An attacker capable of triggering the integer overflow in XPCOM can exploit the boundary condition flaw to escape the sandbox, potentially leading to full system compromise depending on browser privilege level and operating system context.

RemediationAI

Immediately upgrade Mozilla Firefox to version 149 or later, Firefox ESR to version 115.34 or later, or Firefox ESR to version 140.9 or later, depending on your deployment. Organizations on Windows, macOS, and Linux can access automated updates through each platform's respective Firefox update mechanism, or manually download patched versions from https://www.mozilla.org/firefox/. For enterprises managing Firefox centrally, update deployment should be prioritized within 24-48 hours given the sandbox escape severity. Until patching is complete, consider restricting Firefox usage for high-risk activities, enforcing additional endpoint protection (host-based intrusion detection), and monitoring for exploitation attempts targeting XPCOM components. No viable workarounds exist for this sandbox boundary vulnerability, making patching the only effective mitigation.

Affected VersionsENISA

Firefox ESR unspecified <140.9
Firefox ESR unspecified <115.34
Firefox unspecified <149

Affected Packages

euvd firefox_esr_unspecified fix: 115.34, 140.9
euvd firefox_unspecified fix: 149

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

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Technical ContextAI · show details

The vulnerability resides in XPCOM (Cross Platform Component Object Model), Mozilla's component architecture used throughout Firefox for managing internal functionality and extensions. The root cause involves incorrect boundary condition validation combined with integer overflow, categorized under buffer overflow attacks (CWE class). When processing certain XPCOM operations, the integer overflow condition allows an attacker to bypass boundary checks designed to prevent out-of-bounds memory access. This directly undermines Firefox's sandbox isolation mechanism, which typically restricts web content from accessing system resources. The affected products span multiple Firefox variants: standard Firefox (all versions below 149) and two Extended Support Release branches (ESR versions below 115.34 and 140.9), as identified by CPE strings cpe:2.3:a:mozilla:firefox and cpe:2.3:a:mozilla:firefox_esr.

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Severity by source

NVD PRIMARY 8.6 HIGH
AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
SUSE 9.6 CRITICAL
AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Red Hat 7.5 HIGH

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Mar 24, 2026 - 12:30 nvd
HIGH 8.6

DescriptionNVD

Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, and Firefox ESR < 140.9.

Executive ViewAI

Why It Matters

Organizations using the XPCOM component. This vulnerability affects Firefox face significant risk from CVE-2026-4690, a integer overflow vulnerability rated CVSS 8.6. Exploitation could allow attackers to corrupt memory, crash the application, or potentially execute arbitrary code. Organizations should apply vendor updates when available and consider 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 95% exploitable
Data Quality
7 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 HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
Very High
Technical Impact
Total

Priority Score

43
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +43
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Integer Overflow MEDIUM

Integer overflow occurs when an arithmetic operation produces a result that exceeds the maximum value a given integer type can store.

Related Vulnerabilities in Firefox Multiple Component Vulnerabilities

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CVE-2026-4684 HIGH
7.5
CVE-2026-4716 CRITICAL
9.1
CVE-2026-4725 CRITICAL
10.0
CVE-2026-4727 HIGH
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CVE-2026-4728 MEDIUM
6.5
CVE-2026-4692 CRITICAL POC
10.0
CVE-2026-4685 HIGH
7.5
CVE-2026-4686 HIGH
7.5
CVE-2026-4687 HIGH
8.6
CVE-2026-4688 CRITICAL
10.0
CVE-2026-4691 CRITICAL
9.8
CVE-2026-4694 HIGH
7.5
CVE-2026-4705 CRITICAL
9.8
CVE-2026-4724 CRITICAL
9.1

More in Firefox Esr

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CVE-2015-4000 LOW POC
3.7 May 21

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not pro
CVE-2020-26950 HIGH POC
8.8 Dec 09

In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable

CVE-2026-4689 CRITICAL POC
10.0 Mar 24

A sandbox escape vulnerability exists in Firefox's XPCOM component due to incorrect boundary conditions and integer over
CVE-2022-29917 CRITICAL POC
9.8 Dec 22

Mozilla developers Andrew McCreight, Gabriele Svelto, Tom Ritter and the Mozilla Fuzzing Team reported memory safety bug
CVE-2014-1568 HIGH
7.5 Sep 25

Mozilla Network Security Services (NSS) before 3.16.2.1, 3.16.x before 3.16.5, and 3.17.x before 3.17.1, as used in Mozi
CVE-2022-26384 CRITICAL POC
9.6 Dec 22

If an attacker could control the contents of an iframe sandboxed with <code>allow-popups</code> but not <code>allow-scri
CVE-2022-34484 HIGH POC
8.8 Dec 22

The Mozilla Fuzzing Team reported potential vulnerabilities present in Thunderbird 91.10. Rated high severity (CVSS 8.8)
CVE-2022-28281 HIGH POC
8.8 Dec 22

If a compromised content process sent an unexpected number of WebAuthN Extensions in a Register command to the parent pr
CVE-2022-26381 HIGH POC
8.8 Dec 22

An attacker could have caused a use-after-free by forcing a text reflow in an SVG object leading to a potentially exploi
CVE-2022-22756 HIGH POC
8.8 Dec 22

If a user was convinced to drag and drop an image to their desktop or other folder, the resulting object could have been
CVE-2022-22740 HIGH POC
8.8 Dec 22

Certain network request objects were freed too early when releasing a network request handle. Rated high severity (CVSS

CVE-2022-22738 HIGH POC
8.8 Dec 22

Applying a CSS filter effect could have accessed out of bounds memory. Rated high severity (CVSS 8.8), this vulnerabilit

Same weakness CWE-190 – Integer Overflow or Wraparound

View all
CVE-2013-2729 CRITICAL POC
9.8
CVE-2015-8651 HIGH
8.8
CVE-2012-5054 HIGH POC
8.8
CVE-2014-0569 CRITICAL POC
9.3
CVE-2023-21716 CRITICAL POC
9.8
CVE-2017-3599 HIGH POC
7.5
CVE-2026-97229 CRITICAL POC
10.0
CVE-2017-7529 HIGH
7.5

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
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CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

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

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-2026-4690 ADVISORY https://vuldb.com/?id.352739 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://access.redhat.com/errata/RHSA-2026:8850 REF https://access.redhat.com/security/cve/CVE-2026-4690 REF https://bugzilla.mozilla.org/show_bug.cgi?id=2016375 REF https://bugzilla.redhat.com/show_bug.cgi?id=2450732 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4690.json REF https://www.mozilla.org/security/advisories/mfsa2026-20/ REF https://www.mozilla.org/security/advisories/mfsa2026-21/ 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/

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