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Firefox CVE-2026-6769

| EUVDEUVD-2026-24110 HIGH
Improper Privilege Management (CWE-269)
2026-04-21 mozilla GHSA-35h9-jh69-pc24
8.8
CVSS 3.1 · Vendor: mozilla
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Attack ChainAIDerived

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

  1. Access
    User browses to malicious website
  2. Delivery
    Crafted JavaScript delivered to Firefox
  3. Exploit
    Debugger component privilege flaw triggered
  4. Execution
    Sandbox escape achieved
  5. Persist
    Arbitrary code execution with elevated privileges
  6. Impact
    System compromise

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V8 - Authorization Least privilege enforcement
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

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

Exploitation Conditions

Requires user interaction with attacker-controlled web content (UI:R per CVSS vector). The vulnerability is exploitable against default Firefox configurations with the Debugger component present (standard installation). No authentication required (PR:N), meaning any remote attacker can attempt exploitation without valid credentials. Network accessibility (AV:N) allows exploitation via malicious websites visited through normal browsing activity. The scope is unchanged (S:U), limiting impact to the vulnerable Firefox component's security context initially, though privilege escalation subsequently breaks that boundary. The non-automatable SSVC classification indicates exploitation requires targeted social engineering to lure victims to malicious sites rather than automated mass exploitation through scanning. Browser-based exploitation typically requires the victim to actively browse to the attack site, providing a human interaction barrier that limits wormable spread compared to fully remote vulnerabilities.

Impact

Real-world risk assessment reveals moderate urgency despite high CVSS 8.8 score. The CVSS vector shows network-accessible exploitation (AV:N) with low complexity (AC:L) requiring no authentication (PR:N), indicating ease of exploitation, but mandatory user interaction (UI:R) creates a significant barrier. SSVC framework confirms no active exploitation detected (Exploitation: none) and classifies as non-automatable (Automatable: no), meaning targeted social engineering is required rather than mass scanning. The technical impact is rated partial by SSVC despite CVSS showing high confidentiality, integrity, and availability impact - this discrepancy warrants verification with vendor technical details. EPSS data not provided, preventing probabilistic exploitation likelihood assessment. The requirement for user interaction with malicious content significantly reduces wormable spread potential. Priority should focus on Firefox deployments where users regularly interact with untrusted web content, particularly in environments without robust sandboxing or endpoint detection. The availability of vendor patches in both standard and ESR channels enables straightforward remediation without requiring workarounds.

Exploit ScenarioDerived

An attacker hosts a malicious website containing specially crafted JavaScript that targets the Firefox Debugger component's privilege management flaw. When a user browses to the attacker-controlled site, the malicious code triggers the vulnerability in the Debugger subsystem, escalating from the browser sandbox to elevated system privileges. The attacker can then execute arbitrary code with higher privileges, potentially accessing sensitive user data, installing malware, or compromising the underlying operating system beyond the browser's intended security boundary.

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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AnalysisAIv2 – Apr 22, 2026

Privilege escalation in Firefox's Debugger component allows remote attackers to gain elevated system privileges after user interaction with a malicious site. Affects Firefox versions prior to 150 and Firefox ESR versions prior to 140.10. CVSS 8.8 severity with network attack vector and no authentication required. SSVC framework indicates no active exploitation detected and non-automatable attack pattern. Vendor-released patches available in Firefox 150 and Firefox ESR 140.10 per Mozilla security advisories MFSA2026-30 through MFSA2026-34.

Earlier versions of this analysis (1)
v1 Apr 21, 2026 - 18:24 CVSS 6.5

Privilege escalation in Firefox's Debugger component allows unauthenticated network attackers to escalate privileges with low complexity. The vulnerability affects Firefox versions prior to 150 and Firefox ESR versions prior to 140.10, enabling attackers to gain elevated permissions within the browser context. Vendor-released patch available in Firefox 150 and Firefox ESR 140.10.

RemediationAI

Upgrade immediately to Firefox 150 or later for standard release channel users, or Firefox ESR 140.10 or later for Extended Support Release deployments. Vendor-released patches are confirmed available per Mozilla Security Advisories MFSA2026-30 (https://www.mozilla.org/security/advisories/mfsa2026-30/) and MFSA2026-32 (https://www.mozilla.org/security/advisories/mfsa2026-32/). Additional advisory details are available in MFSA2026-33 and MFSA2026-34 at https://www.mozilla.org/security/advisories/. If immediate patching is not feasible, implement compensating controls by disabling the Firefox Debugger and Developer Tools via enterprise policy (preference: devtools.debugger.enabled=false and devtools.chrome.enabled=false), though this will break legitimate debugging workflows for developers. Alternatively, restrict Firefox usage to trusted content only through web filtering and block access to untrusted websites, accepting the operational impact of reduced browsing functionality. Monitor endpoint detection systems for unusual privilege escalation attempts originating from Firefox processes.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

This vulnerability resides in Firefox's Debugger component, which provides developer tools for inspecting and debugging web content. The CWE-269 classification indicates an improper privilege management flaw where the component fails to properly restrict elevated operations. The CPE data identifies Mozilla Firefox as the affected product across multiple branches. The Debugger component operates with elevated privileges to instrument running code, and this flaw likely allows web content to escape the browser sandbox and execute operations with higher privileges than intended. The network attack vector (AV:N) combined with the Debugger context suggests the vulnerability can be triggered remotely through crafted web content that interacts with the debugging subsystem, possibly through developer tool APIs accessible to web pages or extensions.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (mozilla) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
SUSE HIGH
Red Hat 6.1 MEDIUM

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

6
Patch released
Apr 29, 2026 - 02:30 nvd
Patch available
Analysis Updated
Apr 22, 2026 - 00:35 vuln.today
v2 - CVSS changed
Severity Changed
Apr 21, 2026 - 21:22 NVD
MEDIUM HIGH
CVSS changed
Apr 21, 2026 - 21:22 NVD
6.5 (MEDIUM) 8.8 (HIGH)
CVSS changed
Apr 21, 2026 - 18:22 NVD
6.5 (MEDIUM)
CVE Published
Apr 21, 2026 - 12:41 nvd
HIGH 8.8

DescriptionCVE.org

Privilege escalation in the Debugger component. This vulnerability was fixed in Firefox 150 and Firefox ESR 140.10.

Executive ViewAI

Why It Matters

CVE-2026-6769 is a high-severity privilege escalation vulnerability in Firefox's Debugger component that allows remote attackers to gain system-level access through malicious websites without requiring user authentication. This affects all Firefox users running versions prior to 150 and ESR users on versions before 140.10, potentially exposing organizational endpoints to lateral movement and data exfiltration if users visit compromised or attacker-controlled sites.

Business Impact: High
Compensating Controls

Vendor-released patch: Firefox 150 and Firefox ESR 140.10. Until patching is complete, restrict user access to high-risk websites through web filtering, disable Firefox Debugger functionality via group policy (set devtools.enabled = false), and monitor for suspicious debugger console activity in security logs.

Threat Intelligence Overview

EPSS Score
0.0%
Top 88% 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
High
Technical Impact
Partial

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

Affected Products (CPE)CVE.org

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
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

Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Liberty Linux 10 Fixed
SUSE Liberty Linux 8 Fixed
SUSE Liberty Linux 9 Fixed
SUSE Linux Enterprise Server 16.0 SUSE Linux Enterprise Server for SAP applications 16.0 Fixed
openSUSE Leap 16.0 Fixed

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