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Mozilla Firefox CVE-2026-6750

| EUVDEUVD-2026-24091 HIGH
Improper Privilege Management (CWE-269)
2026-04-21 mozilla GHSA-hqjc-gx24-xhpp
Privilege Escalation Mozilla
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 visits malicious website
  2. Delivery
    Browser loads crafted WebRender content
  3. Exploit
    Exploit triggers privilege escalation in WebRender
  4. Execution
    Code escapes content process sandbox
  5. Persist
    Execute arbitrary code with elevated privileges
  6. Impact
    Access sensitive browser data or system resources

Vulnerability Assessment

Weakness
CWE
CWE-269
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.

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Exploitation Conditions

Requires user interaction - victim must visit attacker-controlled website or page containing exploit code using vulnerable Firefox version (before 150, ESR before 115.35, or ESR before 140.10). WebRender must be active (enabled by default in modern Firefox since version 87 on most platforms, but may be disabled on older hardware or via about:config gfx.webrender.all=false). Exploitation limited by mandatory user navigation to malicious content - cannot be triggered remotely without social engineering or watering hole attacks. No authentication required (PR:N) and low attack complexity (AC:L) means once user visits malicious page, exploitation is straightforward. Default Firefox configurations are vulnerable; no specific non-default settings required beyond having WebRender enabled.
Impact

Despite the high CVSS score of 8.8, real-world risk is moderated by multiple factors requiring synthesis. The CVSS vector (AV:N/AC:L/PR:N/UI:R) indicates network-based exploitation with low complexity but mandatory user interaction - an attacker must convince users to visit a malicious website. SSVC framework assessment shows 'Exploitation: none' (no confirmed active exploitation), 'Automatable: no' (aligning with UI:R requirement), and 'Technical Impact: partial' (lower than CVSS suggests with C:H/I:H/A:H). These signals suggest this is a serious vulnerability requiring patching, but not an immediate crisis-level threat. No public exploit identified at time of analysis, and absence from typical exploit databases indicates low weaponization. The primary risk is drive-by compromise scenarios where users visit attacker-controlled sites, but Firefox's rapid release cycle and automatic updates significantly reduce exposure window for most users. Prioritize patching for organizations with managed Firefox deployments, particularly those where users regularly visit untrusted sites, but this does not warrant emergency out-of-band updates given the exploitation prerequisites.
Exploit ScenarioDerived

An attacker hosts a malicious website containing specially crafted content targeting the WebRender privilege management flaw. When a user visits this site with a vulnerable Firefox version, the malicious code exploits the WebRender vulnerability to escalate privileges from the restricted content process sandbox to higher browser privileges or potentially system-level access, enabling the attacker to execute arbitrary code, steal browser-stored credentials, access local files, or establish persistence. The low attack complexity (AC:L) suggests exploitation does not require race conditions or complex preparation beyond serving malicious web content.
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 WebRender allows remote attackers to gain elevated access through malicious web content requiring user interaction. Affects Firefox versions before 150, Firefox ESR before 115.35, and Firefox ESR before 140.10. Mozilla released patches in advisories MFSA2026-30 through MFSA2026-34. CVSS 8.8 (High) severity with network attack vector, but exploitation requires user interaction (visiting malicious site). No public exploit identified at time of analysis, with SSVC framework indicating no confirmed exploitation and partial technical impact.

Earlier versions of this analysis (1)
v1 Apr 21, 2026 - 18:24 CVSS 5.3

Privilege escalation in Firefox's WebRender graphics component allows remote unauthenticated attackers to gain elevated privileges with no user interaction required, affecting Firefox 149 and earlier, Firefox ESR 115.34 and earlier, and Firefox ESR 140.9 and earlier. The vulnerability has a CVSS score of 5.3 with network attack vector and low complexity, though impact is limited to confidentiality (partial information disclosure). Mozilla released patched versions (Firefox 150, ESR 115.35, ESR 140.10) to address this issue.

RemediationAI

Vendor-released patches: Upgrade Firefox to version 150 or later, Firefox ESR to version 115.35 or later, or Firefox ESR to version 140.10 or later depending on your release channel. Firefox users with automatic updates enabled will receive patches automatically. Enterprise deployments should update via standard software distribution mechanisms referencing Mozilla Security Advisories MFSA2026-30 through MFSA2026-34 at https://www.mozilla.org/security/advisories/. For environments unable to immediately patch, compensating controls include restricting browser usage to trusted sites only via web filtering/proxy policies (trade-off: significantly limits browser utility and user productivity), deploying Firefox in isolated virtual machines or containers (trade-off: performance overhead and user experience friction), or temporarily switching to alternative browsers until patching is feasible (trade-off: application compatibility issues and user retraining). However, these workarounds provide incomplete protection and patching remains the only complete remediation. Bugzilla tracking: https://bugzilla.mozilla.org/show_bug.cgi?id=2023407.

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Technical ContextAI · show details

WebRender is Mozilla's GPU-based rendering engine written in Rust, introduced to replace the legacy graphics stack. This vulnerability stems from CWE-269 (Improper Privilege Management), indicating the WebRender component fails to properly enforce privilege boundaries between web content and browser processes. The affected CPE (cpe:2.3:a:mozilla:firefox) confirms this impacts the Firefox application specifically. WebRender operates within Firefox's multi-process architecture (Electrolysis/e10s), where content processes should operate with restricted privileges. A flaw in privilege enforcement could allow malicious web content to escape sandboxing restrictions or elevate from content process privileges to parent process or system-level access, breaking the security model that isolates untrusted web content from sensitive browser functions and user system resources.

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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 7.5 HIGH

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

8
Patch released
Apr 29, 2026 - 02:30 nvd
Patch available
Severity Changed
Apr 22, 2026 - 16:22 NVD
HIGH CRITICAL
CVSS changed
Apr 22, 2026 - 16:22 NVD
8.8 (HIGH) 9.8 (CRITICAL)
Analysis Updated
Apr 22, 2026 - 00:41 vuln.today
v2 - CVSS changed
Severity Changed
Apr 21, 2026 - 21:22 NVD
MEDIUM HIGH
CVSS changed
Apr 21, 2026 - 21:22 NVD
5.3 (MEDIUM) 8.8 (HIGH)
CVSS changed
Apr 21, 2026 - 18:22 NVD
5.3 (MEDIUM)
CVE Published
Apr 21, 2026 - 12:40 nvd
HIGH 8.8

DescriptionCVE.org

Privilege escalation in the Graphics: WebRender component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, and Firefox ESR 140.10.

Executive ViewAI

Why It Matters

CVE-2026-6750 is a high-severity privilege escalation vulnerability in Firefox WebRender that allows remote attackers to gain elevated system access when users visit malicious websites. This affects all Firefox users across the organization and poses risk to endpoint security posture, particularly for users who cannot immediately patch or use unpatched ESR versions.

Business Impact: High
Compensating Controls

Vendor-released patch: Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10 (per MFSA2026-30 through MFSA2026-34). Interim mitigations if immediate patching unavailable: restrict user access to untrusted websites via web filtering; disable JavaScript execution in Firefox for high-risk users; enforce browser sandboxing; consider temporary restriction of Firefox use for critical operations until patches deployed.

Threat Intelligence Overview

EPSS Score
0.0%
Top 86% 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 HIGH

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:*:*:*:*:*:*:*:*

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Same weakness CWE-269 – Improper Privilege Management

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Same technique Privilege Escalation

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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

References

Advisories & patches
ADVISORY https://access.redhat.com/errata/RHSA-2026:10757 ADVISORY https://access.redhat.com/errata/RHSA-2026:10766 ADVISORY https://access.redhat.com/errata/RHSA-2026:10767 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-6750 ADVISORY https://vuldb.com/vuln/358446 REF https://access.redhat.com/errata/RHSA-2026:12285 REF https://access.redhat.com/errata/RHSA-2026:13537 REF https://access.redhat.com/errata/RHSA-2026:15892 REF https://access.redhat.com/errata/RHSA-2026:17477 REF https://access.redhat.com/errata/RHSA-2026:17687 REF https://access.redhat.com/errata/RHSA-2026:17688 REF https://access.redhat.com/errata/RHSA-2026:17689 REF https://access.redhat.com/errata/RHSA-2026:17690 REF https://access.redhat.com/errata/RHSA-2026:19041 REF https://access.redhat.com/errata/RHSA-2026:19131 REF https://access.redhat.com/errata/RHSA-2026:19201 REF https://access.redhat.com/errata/RHSA-2026:19348 REF https://access.redhat.com/errata/RHSA-2026:19461 REF https://access.redhat.com/errata/RHSA-2026:19462 REF https://access.redhat.com/errata/RHSA-2026:19463 REF https://access.redhat.com/errata/RHSA-2026:19464 REF https://access.redhat.com/errata/RHSA-2026:19465 REF https://access.redhat.com/errata/RHSA-2026:19466 REF https://access.redhat.com/errata/RHSA-2026:19467 REF https://access.redhat.com/errata/RHSA-2026:19468 REF https://access.redhat.com/errata/RHSA-2026:19469 REF https://access.redhat.com/errata/RHSA-2026:19542 REF https://access.redhat.com/errata/RHSA-2026:19655 REF https://access.redhat.com/errata/RHSA-2026:19704 REF https://access.redhat.com/security/cve/CVE-2026-6750 REF https://bugzilla.mozilla.org/show_bug.cgi?id=2023407 REF https://bugzilla.redhat.com/show_bug.cgi?id=2460102 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6750.json REF https://www.mozilla.org/security/advisories/mfsa2026-30/ REF https://www.mozilla.org/security/advisories/mfsa2026-31/ REF https://www.mozilla.org/security/advisories/mfsa2026-32/ REF https://www.mozilla.org/security/advisories/mfsa2026-33/ REF https://www.mozilla.org/security/advisories/mfsa2026-34/

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