How to Fix CVE-2026-26047: Denial of service via resource consumption in the affected product

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

CVE-2026-26047 is a denial of service via resource consumption in Vendor the affected product. The fix is to apply the vendor patch noted below.

What is CVE-2026-26047?

A denial-of-service vulnerability was identified in Moodle’s TeX formula editor. When rendering TeX content using mimetex, insufficient execution time limits could allow specially crafted formulas to consume excessive server resources. An authenticated user could abuse this behavior to degrade performance or cause service interruption. The CVSS base score is 6.5 (Medium). The official advisory is at https://access.redhat.com/security/cve/CVE-2026-26047.

Am I affected?

Check the version of the affected product you are running and compare it against the Affected row above (0 to <4.5.9; 5.0.0 to <5.0.5; 5.1.0 to <5.1.2). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:

# Linux package check
dpkg -s the-affected-product 2>/dev/null | grep -i ^Version
rpm -q the-affected-product 2>/dev/null
command -v the-affected-product >/dev/null && the-affected-product --version 2>/dev/null

# Windows (PowerShell)
Get-Package -Name "*the affected product*" -ErrorAction SilentlyContinue | Select-Object Name, Version
winget list --name "the affected product" 2>$null

How to fix CVE-2026-26047

Upgrade the affected product to a patched build: See vendor advisory. 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 the-affected-product
dpkg -s the-affected-product | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux

sudo dnf upgrade --refresh the-affected-product -y
# or for older releases:
sudo yum update the-affected-product -y
rpm -q the-affected-product

SUSE / openSUSE

sudo zypper refresh
sudo zypper update the-affected-product
rpm -q the-affected-product

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2026-26047 affecting the affected product
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-26047-fix-$(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"
    $pkg = Get-Package -Name "*the affected product*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "the affected product" --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 "the affected product"
    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-2026-26047 affecting the affected product
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-26047-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 the-affected-product 2>/dev/null | grep -i ^Version || echo "the-affected-product not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q the-affected-product || echo "the-affected-product not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-26047-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/the-affected-product /etc/the-affected-product.d /etc/the-affected-product.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: See vendor advisory)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y the-affected-product
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y the-affected-product
elif command -v yum >/dev/null; then
    yum update -y the-affected-product
elif command -v zypper >/dev/null; then
    zypper --non-interactive update the-affected-product
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s the-affected-product 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q the-affected-product
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-2026-26047" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-26047"

Disable the affected service (Linux)

sudo systemctl stop the-affected-product 2>/dev/null || true
sudo systemctl disable the-affected-product 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 the-affected-product 2>/dev/null | grep -i ^Version
rpm -q the-affected-product 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 "*the affected product*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above See vendor advisory. Restart the affected service (systemctl restart <service> on Linux, or restart the Windows service) so it loads the patched binary.

Frequently asked questions

Related fixes

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

• How to Fix CVE-2026-28133: Unrestricted file upload in Filr — Unrestricted file upload in Filr
• How to Fix CVE-2026-21724: Critical Vulnerability in Grafana OSS — Critical Vulnerability in Grafana OSS
• How to Fix CVE-2026-25986: Out-of-bounds write in ImageMagick , Out-of-bounds write in ImageMagick
• How to Fix CVE-2026-25627: Path Traversal in nanomq , Path Traversal in nanomq
• How to Fix CVE-2026-41299: Reliance on untrusted inputs in a in OpenClaw , Reliance on untrusted inputs in a in OpenClaw

Is CVE-2026-26047 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-2026-26047?

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-2026-26047?

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

Where is the official advisory for CVE-2026-26047?

The vendor advisory is at https://access.redhat.com/security/cve/CVE-2026-26047. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-26047.

References

• Official vendor advisory: https://access.redhat.com/security/cve/CVE-2026-26047
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-26047
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Additional reference: https://bugzilla.redhat.com/show_bug.cgi?id=2440905

*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.*