⚠ 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 4.9

How to Fix CVE-2026-0871: Incorrect privilege assignment in Red Hat build of Keycloak 26.4

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

CVE-2026-0871 is a incorrect privilege assignment in Red Hat Red Hat build of Keycloak 26.4. The fix is to upgrade to Red Hat build of Keycloak 26.4 26.4-10; Red Hat build of Keycloak 26.4 26.4-11; Red Hat build of Keycloak 26.4 26.4.9-1.

⚡ At a glance
Severity4.9 (Medium)
Actively exploited?No public listing in CISA KEV
AffectedSee vendor advisory
Fixed inRed Hat build of Keycloak 26.4 26.4-10; Red Hat build of Keycloak 26.4 26.4-11; Red Hat build of Keycloak 26.4 26.4.9-1
Type (CWE)CWE-266: Incorrect Privilege Assignment

What is CVE-2026-0871?

A flaw was found in Keycloak. An administrator with manage-users permission can bypass the "Only administrators can view" setting for unmanaged attributes, allowing them to modify these attributes. This improper access control can lead to unauthorized changes to user profiles, even when the system is configured to restrict such modifications. The CVSS base score is 4.9 (Medium). The official advisory is at https://access.redhat.com/errata/RHSA-2026:2365.

Am I affected?

Check the version of Red Hat build of Keycloak 26.4 you are running and compare it against the Affected row above (See vendor advisory). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


# Linux package check
dpkg -s red-hat-build-of-keycloak-26-4 2>/dev/null | grep -i ^Version
rpm -q red-hat-build-of-keycloak-26-4 2>/dev/null
command -v red-hat-build-of-keycloak-26-4 >/dev/null && red-hat-build-of-keycloak-26-4 --version 2>/dev/null


# Windows (PowerShell)
Get-Package -Name "*Red Hat build of Keycloak 26.4*" -ErrorAction SilentlyContinue | Select-Object Name, Version
winget list --name "Red Hat build of Keycloak 26.4" 2>$null

How to fix CVE-2026-0871

Upgrade Red Hat build of Keycloak 26.4 to a patched build: Red Hat build of Keycloak 26.4 26.4-10; Red Hat build of Keycloak 26.4 26.4-11; Red Hat build of Keycloak 26.4 26.4.9-1. The vendor advisory is the source of truth for the exact fixed version.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade red-hat-build-of-keycloak-26-4
dpkg -s red-hat-build-of-keycloak-26-4 | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


sudo dnf upgrade --refresh red-hat-build-of-keycloak-26-4 -y
# or for older releases:
sudo yum update red-hat-build-of-keycloak-26-4 -y
rpm -q red-hat-build-of-keycloak-26-4

SUSE / openSUSE


sudo zypper refresh
sudo zypper update red-hat-build-of-keycloak-26-4
rpm -q red-hat-build-of-keycloak-26-4

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-0871 affecting Red Hat build of Keycloak 26.4
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-0871-fix-$(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] Detect installed version"
    $pkg = Get-Package -Name "*Red Hat build of Keycloak 26.4*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

    Write-Host "[2/4] Backup configuration"
    $backup = "C:\Backup\red-hat-build-of-keycloak-26-4-$(Get-Date -Format yyyyMMdd)"
    New-Item -ItemType Directory -Force $backup | Out-Null
    Get-ChildItem "C:\ProgramData\Red Hat build of Keycloak 26.4" -ErrorAction SilentlyContinue |
        Copy-Item -Destination $backup -Recurse -Force -ErrorAction SilentlyContinue

    Write-Host "[3/4] Apply the upgrade to Red Hat build of Keycloak 26.4 26.4-10; Red Hat build of Keycloak 26.4 26.4-11; Red Hat build of Keycloak 26.4 26.4.9-1"
    winget upgrade --name "Red Hat build of Keycloak 26.4" --silent --accept-source-agreements --accept-package-agreements
    if ($LASTEXITCODE -ne 0) {
        # Fallback: pull latest via OS update channel
        Install-Module -Name PSWindowsUpdate -Force -SkipPublisherCheck -ErrorAction SilentlyContinue
        Import-Module PSWindowsUpdate
        Install-WindowsUpdate -MicrosoftUpdate -AcceptAll -IgnoreReboot
    }

    Write-Host "[4/4] Verify the patched build"
    winget list --name "Red Hat build of Keycloak 26.4"
    Write-Host "Patch 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-2026-0871 affecting Red Hat build of Keycloak 26.4
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-0871-fix-$(date +%Y%m%d-%H%M%S).log"
exec > >(tee -a "$LOG") 2>&1

echo "[1/4] Detect installed version"
if command -v dpkg >/dev/null; then
    dpkg -s red-hat-build-of-keycloak-26-4 2>/dev/null | grep -i ^Version || echo "red-hat-build-of-keycloak-26-4 not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q red-hat-build-of-keycloak-26-4 || echo "red-hat-build-of-keycloak-26-4 not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-0871-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/red-hat-build-of-keycloak-26-4 /etc/red-hat-build-of-keycloak-26-4.d /etc/red-hat-build-of-keycloak-26-4.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: Red Hat build of Keycloak 26.4 26.4-10; Red Hat build of Keycloak 26.4 26.4-11; Red Hat build of Keycloak 26.4 26.4.9-1)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y red-hat-build-of-keycloak-26-4
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y red-hat-build-of-keycloak-26-4
elif command -v yum >/dev/null; then
    yum update -y red-hat-build-of-keycloak-26-4
elif command -v zypper >/dev/null; then
    zypper --non-interactive update red-hat-build-of-keycloak-26-4
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s red-hat-build-of-keycloak-26-4 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q red-hat-build-of-keycloak-26-4
fi
echo "Done. Restart any service that loaded the old library."

If you can't patch immediately

Apply at least one of the following inline controls until you can deploy the patched build. None replace the upgrade.

Restrict exposure with nftables (Linux)


# Allow only trusted CIDR to reach the affected service ports
sudo nft add table inet filter 2>/dev/null || true
sudo nft 'add chain inet filter input { type filter hook input priority 0 ; }' 2>/dev/null || true
sudo nft 'add rule inet filter input tcp dport {80, 443} ip saddr != 10.0.0.0/8 drop'
sudo nft list ruleset

Block at the host firewall (Windows)


New-NetFirewallRule -DisplayName "Block-CVE-2026-0871" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-0871"

Disable the affected service (Linux)


sudo systemctl stop red-hat-build-of-keycloak-26-4 2>/dev/null || true
sudo systemctl disable red-hat-build-of-keycloak-26-4 2>/dev/null || true

If the vendor advisory lists an official workaround, prefer that wording verbatim. If no workaround is published, the only safe remediation is the patch.

How to verify the fix worked

After upgrading, confirm the installed version matches the patched build and that no old library is still loaded by a long-running process.


# Linux
dpkg -s red-hat-build-of-keycloak-26-4 2>/dev/null | grep -i ^Version
rpm -q red-hat-build-of-keycloak-26-4 2>/dev/null || true
# Pid map check for old library handles
sudo lsof +c0 2>/dev/null | grep -i "DEL.*lib" || true


# Windows
Get-Package -Name "*Red Hat build of Keycloak 26.4*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above Red Hat build of Keycloak 26.4 26.4-10; Red Hat build of Keycloak 26.4 26.4-11; Red Hat build of Keycloak 26.4 26.4.9-1. Restart the affected service (systemctl restart <service> on Linux, or restart the Windows service) so it loads the patched binary.

Frequently asked questions

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

Is CVE-2026-0871 actively exploited?

There is no public confirmation of exploitation in the wild listed in CISA KEV at the time of this writing. Patch anyway. Public exploits commonly follow disclosure within weeks.

Do I need to reboot after patching CVE-2026-0871?

For kernel and OS-level updates, yes. For most userland packages a systemctl restart <service> is enough on Linux, and restarting the Windows service or app on Windows. Any process that loaded the old library keeps using it until restarted.

What is the CVSS score for CVE-2026-0871?

4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N.

Where is the official advisory for CVE-2026-0871?

The vendor advisory is at https://access.redhat.com/errata/RHSA-2026:2365. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-0871.

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.*