Patch

CVE-2025-21399

with vRx

Vulnerability Overview

CVE Name

CVE-2025-21399

Severity

7.4

High

CVE Description

Microsoft Edge (Chromium-based) Update Elevation of Privilege Vulnerability

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Latest Patch info

There is no patch available at the moment, but you can use our script.

Patch Name

Date

Script

Script Type

Remediation script

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❗ CVE-2025-21399 is a privilege escalation vulnerability affecting the update mechanism of Microsoft Edge (Chromium-based), carrying a CVSS score of 7.4. This flaw allows an attacker to obtain elevated privileges on the affected system, potentially enabling unauthorized actions that could compromise user data and system integrity. ℹ️ This mitigation script works as follows: Service Disabling: Stops and disables the edgeupdate and edgeupdatem services. Prevents the Edge Update process from running automatically. Executable Renaming: Renames MicrosoftEdgeUpdate.exe to MicrosoftEdgeUpdate_Disabled.exe in default installation paths to prevent it from being launched by other means. Blocks the updater from being executed. Registry Configuration: Disables Microsoft Edge automatic updates by setting the AutoUpdateCheckPeriodMinutes registry value to 0. Ensures the registry path exists and is properly configured. ACL Enforcement: Applies a Deny Write rule for BUILTIN\Users on the Edge Update directories. Prevents non-admin users from modifying or replacing the updater executable. Error Handling: Provides detailed feedback on each step, including failures or skipped actions. Handles missing files, directories, or permission issues effectively. ✅ By running this mitigation script, you can reduce the risk of exploitation for CVE-2025-21399 by disabling the vulnerable update mechanism and enforcing strict access controls.

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#Requires -RunAsAdministrator

if (-not ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
    Write-Host "This script must be run as Administrator. Exiting." -ForegroundColor Red
    exit 1
}

$executablePaths = @(
    "C:\Program Files (x86)\Microsoft\EdgeUpdate\MicrosoftEdgeUpdate.exe",
    "C:\Program Files\Microsoft\EdgeUpdate\MicrosoftEdgeUpdate.exe"
)

# 1. Disable services
@("edgeupdate", "edgeupdatem") | ForEach-Object {
    try {
        Write-Host "Disabling service: $_" -ForegroundColor Cyan
        Stop-Service -Name $_ -Force
        Set-Service -Name $_ -StartupType Disabled
    } catch {
        Write-Host "Service $_ not found or error: $_" -ForegroundColor Yellow
    }
}

# 2. Rename executables
foreach ($path in $executablePaths) {
    if (Test-Path $path) {
        try {
            $renamedPath = $path -replace "MicrosoftEdgeUpdate.exe$", "MicrosoftEdgeUpdate_Disabled.exe"
            Stop-Process -Name "MicrosoftEdgeUpdate" -Force -ErrorAction SilentlyContinue
            Rename-Item -Path $path -NewName $renamedPath -Force
            Write-Host "Renamed: $path → $renamedPath" -ForegroundColor Green
        } catch {
            Write-Host "Rename failed for $path : $_" -ForegroundColor Red
        }
    }
}

# 3. Disable registry updates
try {
    $policyPath = "HKLM:\SOFTWARE\Policies\Microsoft\EdgeUpdate"
    if (-not (Test-Path $policyPath)) { New-Item -Path $policyPath -Force | Out-Null }
    Set-ItemProperty -Path $policyPath -Name "AutoUpdateCheckPeriodMinutes" -Value 0 -Type DWord
    Write-Host "Disabled auto-updates in registry" -ForegroundColor Green
} catch {
    Write-Host "Registry update failed: $_" -ForegroundColor Red
}

# 4. Apply ACLs
foreach ($path in $executablePaths) {
    $dir = Split-Path $path -Parent
    if (Test-Path $dir) {
        try {
            $acl = Get-Acl $dir
            $rule = New-Object System.Security.AccessControl.FileSystemAccessRule(
                "BUILTIN\Users",
                "Write,Modify,Delete",
                "ContainerInherit,ObjectInherit",
                "None",
                "Deny"
            )
            $acl.AddAccessRule($rule)
            Set-Acl -Path $dir -AclObject $acl
            Write-Host "Applied deny ACL to: $dir" -ForegroundColor Green
        } catch {
            Write-Host "ACL failed for $dir : $_" -ForegroundColor Red
        }
    }
}

Write-Host "`n[+] MITIGATIONS APPLIED." -ForegroundColor Green
exit 0

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Affected OS & Apps

No items found.

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