⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● High · CVSS 7.7

How to Fix CVE-2026-40683: Access of resource using incompatible type in Keystone

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

⚡ At a glance
Severity7.7 (High)
Actively exploited?No public listing in CISA KEV
AffectedOpenStack Keystone 8.0.0 to <25.0.1, 26.0.0 to <26.1.1, 27.0.0 to <27.0.1, 28.0.0 to <28.0.1
Fixed inKeystone 25.0.1; Keystone 26.1.1; Keystone 27.0.1; Keystone 28.0.1
Type (CWE)CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')

What is CVE-2026-40683?

In OpenStack Keystone before 28.0.1, the LDAP identity backend does not convert the user enabled attribute to a boolean when the user_enabled_invert configuration option is False (the default). The _ldap_res_to_model method in the UserApi class only performed string-to-boolean conversion when user_enabled_invert was True. When False, the raw string value from LDAP (e.g., "FALSE") was used directly. Since non-empty strings are truthy in Python, users marked as disabled in LDAP were treated as enabled by Keystone, allowing them to authenticate and perform actions.

Am I affected?

Run the version check that matches your platform:


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

Compare what you see against the Affected row above (OpenStack Keystone 8.0.0 to <25.0.1, 26.0.0 to <26.1.1, 27.0.0 to <27.0.1, 28.0.0 to <28.0.1). If your build sits inside that range, you are exposed and should patch.

How to fix CVE-2026-40683

The primary fix is to upgrade Keystone to the patched build. Use the commands for your platform below; the patched versions listed in the vendor advisory are: Keystone 25.0.1; Keystone 26.1.1; Keystone 27.0.1; Keystone 28.0.1.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade keystone
keystone --version 2>/dev/null || dpkg -s keystone | grep -i version

RHEL / CentOS / Rocky / AlmaLinux


sudo dnf upgrade --security keystone -y
rpm -q keystone

SUSE / openSUSE


sudo zypper patch --category security
rpm -q keystone

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-40683 affecting Keystone
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-40683-fix-$(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 Keystone"
    $pkg = winget list --id "Keystone" 2>$null
    Write-Host $pkg

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

    Write-Host "[3/4] Applying upgrade to Keystone 25.0.1; Keystone 26.1.1; Keystone 27.0.1; Keystone 28.0.1"
    winget upgrade --id "Keystone" --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 "Keystone"
    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-2026-40683 affecting Keystone
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-40683-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 keystone 2>/dev/null | grep -i version || echo "keystone not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q keystone || echo "keystone not installed via rpm"
fi

echo "[2/4] Backing up configuration"
BACKUP="/root/backup-cve-2026-40683-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/keystone /etc/keystone.d /etc/keystone.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Applying upgrade (target: Keystone 25.0.1; Keystone 26.1.1; Keystone 27.0.1; Keystone 28.0.1)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y keystone
elif command -v dnf >/dev/null; then
    dnf upgrade --security -y keystone
elif command -v yum >/dev/null; then
    yum update -y keystone
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 keystone 2>/dev/null | grep -i version
elif command -v rpm >/dev/null; then
    rpm -q keystone
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.

Network restriction (Linux, nftables)


# Block inbound traffic to the affected service from untrusted networks
sudo nft add table inet filter
sudo nft 'add chain inet filter input { type filter hook input priority 0 ; }'
sudo nft 'add rule inet filter input tcp dport {443, 80} ip saddr != 10.0.0.0/8 drop'
sudo nft list ruleset

Service-level fallback


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

How to verify the fix worked


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


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

Expected: the reported version is at or above Keystone 25.0.1; Keystone 26.1.1; Keystone 27.0.1; Keystone 28.0.1. 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-2026-40683 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?

7.7 (high). 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.*