⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● Medium · CVSS 6.8

How to Fix CVE-2026-40191: Incorrect authorization in clearancekit

By Sai Kiran Pandrala. Last verified: 2026-05-25.

⚡ At a glance
Severity6.8 (Medium)
Actively exploited?No public listing in CISA KEV
Affectedcraigjbass clearancekit < 5.0.4-beta-1f46165
Fixed inclearancekit 5.0.4-beta-1f46165
Type (CWE)CWE-863: CWE-863: Incorrect Authorization

What is CVE-2026-40191?

ClearanceKit intercepts file-system access events on macOS and enforces per-process access policies. Prior to 5.0.4-beta-1f46165, ClearanceKit's Endpoint Security event handler only checked the source path of dual-path file operations against File Access Authorization (FAA) rules and App Jail policies. The destination path was ignored entirely. This allowed any local process to bypass file-access protection by using rename, link, copyfile, exchangedata, or clone operations to place or replace files inside protected directories.

Am I affected?

Run the version check that matches your platform:


# Windows
winget list | findstr /I "clearancekit"
Get-WmiObject Win32_Product | Where-Object { $_.Name -like "*clearancekit*" } | Select-Object Name, Version


# macOS
sw_vers
brew list --versions clearancekit 2>/dev/null

Compare what you see against the Affected row above (craigjbass clearancekit < 5.0.4-beta-1f46165). If your build sits inside that range, you are exposed and should patch.

How to fix CVE-2026-40191

The primary fix is to upgrade clearancekit to the patched build. Use the commands for your platform below; the patched version listed in the vendor advisory is: clearancekit 5.0.4-beta-1f46165.

Windows (PowerShell, run as administrator)


# Check installed version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

# Apply latest Microsoft security updates (Windows Update)
Install-Module -Name PSWindowsUpdate -Force -SkipPublisherCheck
Import-Module PSWindowsUpdate
Get-WindowsUpdate -MicrosoftUpdate
Install-WindowsUpdate -MicrosoftUpdate -AcceptAll -AutoReboot

# Or via winget for application-level patches
winget upgrade --all --accept-source-agreements --accept-package-agreements

If the affected component is a third-party application, identify the package and run:


winget upgrade --id <vendor.product>

Replace <vendor.product> with the actual winget identifier (run winget search clearancekit to find it).

macOS


# System updates (Apple-issued patches)
softwareupdate --list
sudo softwareupdate --install --all --restart

# For third-party tools managed by Homebrew
brew update
brew upgrade

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-40191 affecting clearancekit
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-40191-fix-$(Get-Date -Format yyyyMMdd-HHmmss).log"
New-Item -ItemType Directory -Force (Split-Path $LogPath) | Out-Null
Start-Transcript -Path $LogPath -Append

try {
    Write-Host "[1/4] Detecting installed version of clearancekit"
    $pkg = winget list --id "clearancekit" 2>$null
    Write-Host $pkg

    Write-Host "[2/4] Backing up configuration"
    $backup = "C:\Backup\clearancekit-$(Get-Date -Format yyyyMMdd)"
    New-Item -ItemType Directory -Force $backup | Out-Null
    Get-ChildItem "C:\ProgramData\clearancekit" -ErrorAction SilentlyContinue |
        Copy-Item -Destination $backup -Recurse -Force -ErrorAction SilentlyContinue

    Write-Host "[3/4] Applying upgrade to clearancekit 5.0.4-beta-1f46165"
    winget upgrade --id "clearancekit" --silent --accept-source-agreements --accept-package-agreements
    # Fallback: Windows Update for OS-level fixes
    if ($LASTEXITCODE -ne 0) {
        Install-Module -Name PSWindowsUpdate -Force -SkipPublisherCheck -ErrorAction SilentlyContinue
        Import-Module PSWindowsUpdate
        Install-WindowsUpdate -MicrosoftUpdate -AcceptAll -IgnoreReboot
    }

    Write-Host "[4/4] Verifying patched build"
    winget list --id "clearancekit"
    Write-Host "Fix applied. Reboot if prompted."
    exit 0
} catch {
    Write-Error "Patch failed: $_"
    exit 1
} finally {
    Stop-Transcript
}

Complete Bash remediation script (Linux)


#!/usr/bin/env bash
# Fix script for CVE-2026-40191 affecting clearancekit
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-40191-fix-$(date +%Y%m%d-%H%M%S).log"
exec > >(tee -a "$LOG") 2>&1

echo "[1/4] Detecting installed version"
if command -v dpkg >/dev/null; then
    dpkg -s clearancekit 2>/dev/null | grep -i version || echo "clearancekit not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q clearancekit || echo "clearancekit not installed via rpm"
fi

echo "[2/4] Backing up configuration"
BACKUP="/root/backup-cve-2026-40191-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/clearancekit /etc/clearancekit.d /etc/clearancekit.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Applying upgrade (target: clearancekit 5.0.4-beta-1f46165)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y clearancekit
elif command -v dnf >/dev/null; then
    dnf upgrade --security -y clearancekit
elif command -v yum >/dev/null; then
    yum update -y clearancekit
elif command -v zypper >/dev/null; then
    zypper --non-interactive patch --category security
fi

echo "[4/4] Verifying patched build"
if command -v dpkg >/dev/null; then
    dpkg -s clearancekit 2>/dev/null | grep -i version
elif command -v rpm >/dev/null; then
    rpm -q clearancekit
fi
echo "Done. Restart any running daemons that loaded the old library."

If you can't patch immediately

If you cannot apply the patched version today, restrict exposure with one of the following runnable controls. None replace the patch.

Windows firewall isolation


# Allow only management subnet to reach the vulnerable service
New-NetFirewallRule -DisplayName "Restrict clearancekit" `
    -Direction Inbound -Action Block -RemoteAddress Any `
    -Protocol TCP -LocalPort 443
New-NetFirewallRule -DisplayName "Allow Mgmt clearancekit" `
    -Direction Inbound -Action Allow -RemoteAddress 10.0.0.0/8 `
    -Protocol TCP -LocalPort 443

Service-level fallback


# If the affected feature is optional, stop the service until the patch is applied
sudo systemctl stop clearancekit
sudo systemctl disable clearancekit

How to verify the fix worked


# Linux
clearancekit --version 2>/dev/null || dpkg -s clearancekit | grep -i version
rpm -q clearancekit 2>/dev/null || true


# Windows
winget list | findstr /I "clearancekit"
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above clearancekit 5.0.4-beta-1f46165. Restart any services that loaded the old library (systemctl restart <service> on Linux, restart the Windows service or reboot when prompted). For network appliances, run show version on the device and confirm the build matches the patched release.

Frequently asked questions

Other vulnerabilities in the same area that are worth patching alongside this one:

Is CVE-2026-40191 actually being exploited?

According to the data sources above, no public confirmation of in-the-wild exploitation at this time. Either way, the fix is the same: apply the vendor patch.

Do I need to reboot after patching?

For OS or kernel updates, yes. For most userland packages a systemctl restart <service> is enough. Any process that loaded the old shared library keeps using it until restarted, so when in doubt, reboot.

What is the CVSS score?

6.8 (medium). Refer to the vendor advisory for the exact vector string.

Where is the official advisory?

See the References section at the bottom of this page; the vendor's URL is the authoritative source for affected builds and patched versions.

References

*Written by Sai Kiran Pandrala. Assembled from the official vendor advisory, NVD record, and CISA KEV listing on 2026-05-25. Always confirm against the vendor's advisory before applying changes in production.*