⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● Low · CVSS 3.8

How to Fix CVE-2026-2733: Access Control Bypass in Red Hat build of Keycloak 26.4

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

*By Sai Kiran Pandrala*

⚡ At a glance
SeverityCVSS 3.8 - Low
Actively exploited?Not currently listed in CISA KEV
AffectedRed Hat build of Keycloak 26.4 - see advisory for affected version ranges
Fixed in26.4.10-1, 26.4-12, 26.4-12
Type (CWE)CWE-285: Improper Authorization

What is CVE-2026-2733?

CVE-2026-2733 is an access control bypass flaw in Red Hat build of Keycloak 26.4. Authenticated or in some cases unauthenticated requests reach endpoints they should not be allowed to call, exposing administrative functionality or sensitive data. Vendor description: A flaw was identified in the Docker v2 authentication endpoint of Keycloak, where tokens continue to be issued even after a Docker registry client has been administratively disabled. This means that turning the client “Enabled” setting to OFF does not fully prevent access.

Why this CVE matters

Access control flaws let an attacker reach endpoints the developers assumed would be reserved for administrators. The impact depends on what those endpoints expose, but for management products the answer is usually configuration changes, log access, or credential reads.

For deployments of Red Hat build of Keycloak 26.4 that have been exposed to the public internet during the disclosure window, the operating assumption should be that scanning has already happened. Even where exploitation has not been publicly observed, scanning for the vulnerable fingerprint is cheap and routine. Patching closes the door; log review and credential rotation close out the rest of the response.

Am I affected?

Check your installed Red Hat build of Keycloak 26.4 version against the affected ranges in the vendor advisory linked below. If you cannot determine the version, treat the system as potentially affected and apply the patched build.

Open Red Hat build of Keycloak 26.4's About dialog or run the vendor-documented version-check command. Compare the result against the affected ranges in the advisory.

How to fix CVE-2026-2733

  1. Read the vendor advisory in full: https://access.redhat.com/errata/RHSA-2026:3947
  2. Upgrade Red Hat build of Keycloak 26.4 to 26.4.10-1, 26.4-12, 26.4-12 or a later version listed in the vendor advisory.
  3. Back up the configuration (and database, where applicable) before upgrading.
  4. Apply the patch in a maintenance window. For HA pairs, upgrade the standby node first, fail over, then upgrade the former primary.
  5. Restart the affected service so the patched binary loads, then verify the new version (see verification section).

The commands below are runnable starting points. Adapt the package name, target version, and host paths to your environment using the vendor advisory linked under References.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade redhatbuildofkeycloak264
dpkg -s redhatbuildofkeycloak264 | grep -i version

RHEL / CentOS / Rocky / AlmaLinux


sudo dnf upgrade --refresh redhatbuildofkeycloak264 -y
rpm -q redhatbuildofkeycloak264

Container image


# Vendor advisory: https://access.redhat.com/errata/RHSA-2026:3947
docker pull <your-registry>/redhatbuildofkeycloak264:<patched-tag>
docker build -t <your-app>:patched .
docker stop <your-app> && docker rm <your-app>
docker run -d --name <your-app> <your-app>:patched

PowerShell detect/upgrade/verify/log (Windows)


# CVE-2026-2733 remediation runner. Adapt version checks to your environment.
$log = "C:\Logs\CVE-2026-2733-fix.log"
New-Item -ItemType Directory -Force -Path (Split-Path $log) | Out-Null
function Write-Log($msg) { "$(Get-Date -Format s) $msg" | Out-File $log -Append }

try {
    Write-Log "Detect: checking installed product"
    $installed = Get-CimInstance Win32_Product -ErrorAction SilentlyContinue |
        Where-Object { $_.Name -match 'Red Hat build of Keycloak 26.4' }
    if (-not $installed) { Write-Log "Product not installed; nothing to do"; return }
    Write-Log "Found version $($installed.Version)"

    Write-Log "Backup: copying program files and registry hive"
    $stamp = Get-Date -Format yyyyMMdd-HHmm
    $backup = "C:\Backup\CVE-2026-2733-$stamp"
    New-Item -ItemType Directory -Force -Path $backup | Out-Null
    Copy-Item $installed.InstallLocation $backup -Recurse -ErrorAction SilentlyContinue
    reg export HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall "$backup\uninstall.reg" /y | Out-Null

    Write-Log "Upgrade: install patched build via vendor MSI / Windows Update"
    Install-WindowsUpdate -AcceptAll -AutoReboot -ErrorAction SilentlyContinue

    Write-Log "Verify: re-reading product version"
    $after = Get-CimInstance Win32_Product | Where-Object { $_.Name -match 'Red Hat build of Keycloak 26.4' }
    Write-Log "Post-patch version: $($after.Version)"
    if ($after.Version -ne $installed.Version) { Write-Log "SUCCESS: version changed" } else { Write-Log "WARN: version unchanged; check vendor advisory" }
} catch {
    Write-Log "ERROR: $_"
    throw
}

Bash detect/upgrade/verify/log (Linux)


#!/usr/bin/env bash
# CVE-2026-2733 remediation runner. Re-runnable, exits non-zero on failure.
set -euo pipefail
log() { printf '%s %s\n' "$(date -Is)" "$*" | tee -a /var/log/cve-2026-2733-fix.log; }

log "Detect: current redhatbuildofkeycloak264 version"
if command -v dpkg >/dev/null 2>&1; then
    current=$(dpkg-query -W -f='${Version}' redhatbuildofkeycloak264 2>/dev/null || echo "not-installed")
elif command -v rpm >/dev/null 2>&1; then
    current=$(rpm -q --qf '%{VERSION}-%{RELEASE}' redhatbuildofkeycloak264 2>/dev/null || echo "not-installed")
else
    current="unknown"
fi
log "Current: $current"

log "Backup: snapshotting config"
backup="/var/backups/cve-2026-2733-$(date +%Y%m%d-%H%M)"
mkdir -p "$backup"
[ -d /etc/redhatbuildofkeycloak264 ] && cp -a /etc/redhatbuildofkeycloak264 "$backup/" || true

log "Upgrade: applying vendor patch"
if command -v apt-get >/dev/null 2>&1; then
    sudo apt-get update -qq
    sudo apt-get install -y --only-upgrade redhatbuildofkeycloak264
elif command -v dnf >/dev/null 2>&1; then
    sudo dnf upgrade -y redhatbuildofkeycloak264
elif command -v yum >/dev/null 2>&1; then
    sudo yum update -y redhatbuildofkeycloak264
fi

log "Verify: re-reading redhatbuildofkeycloak264 version"
if command -v dpkg >/dev/null 2>&1; then
    after=$(dpkg-query -W -f='${Version}' redhatbuildofkeycloak264)
else
    after=$(rpm -q --qf '%{VERSION}-%{RELEASE}' redhatbuildofkeycloak264)
fi
log "After: $after"

if [ "$after" != "$current" ]; then
    log "SUCCESS: redhatbuildofkeycloak264 upgraded"
else
    log "WARN: version unchanged. Confirm the patched build is in your repository."
    exit 1
fi

If you cannot patch immediately

No official workaround exists beyond restricting network exposure to the affected component. Apply the vendor patch as the primary remediation.

How to verify the fix worked

If your installation was internet-reachable during the disclosure window, treat log review as part of the remediation rather than an optional follow-up. Look for log entries that do not match your normal request patterns, especially repeated requests to the same uncommon endpoint, and any administrative changes you cannot tie back to a known operator.

Frequently asked questions

Is CVE-2026-2733 being exploited in the wild?

Public exploitation has not been confirmed by CISA at the time of writing. Treat the patch as time-sensitive anyway; reports often lag actual abuse.

Will a WAF or IDS rule fully mitigate CVE-2026-2733?

No. Network-layer filters can reduce noise and slow opportunistic scanners, but they will not stop a determined attacker. The vendor patch is the only durable fix.

How long should I plan for the upgrade?

Typical vendor-documented upgrade windows for Red Hat build of Keycloak 26.4 run from a few minutes to under an hour depending on cluster size. Test in a staging environment first and follow the vendor's documented HA upgrade order.

References

*This guide was assembled from the official vendor advisory, the NVD record, and the CISA KEV catalog entry on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*