How to Fix CVE-2026-26984: Path traversal in Loris

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

CVE-2026-26984 is a path traversal in aces Loris. The fix is to apply the vendor patch noted below.

What is CVE-2026-26984?

LORIS (Longitudinal Online Research and Imaging System) is a self-hosted web application that provides data- and project-management for neuroimaging research. Prior to versions 26.0.5, 27.0.2, and 28.0.0, an authenticated user with sufficient privileges can exploit a path traversal vulnerability to upload a malicious file to an arbitrary location on the server. Once uploaded, the file can be used to achieve remote code execution (RCE). An attacker must be authenticated and have the appropriate permissions to exploit this issue. If the server is configured as read-only, remote code execution (RCE) is not possible; however, the malicious file upload may still be achievable. This problem is fixed in LORIS v26.0.5 and above, v27.0.2 and above, and v28.0.0 and above. As a workaround, LORIS administrators can disable the media module if it is not being used. The CVSS base score is 8.7 (High), which puts this in the upper risk band and warrants a fast patch cycle. The official advisory is at https://github.com/aces/Loris/security/advisories/GHSA-mpgc-c48m-6v2h.

Am I affected?

Check the version of Loris you are running and compare it against the Affected row above (Loris < 26.0.5; Loris >= 27.0.0, < 27.0.2). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:

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

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

How to fix CVE-2026-26984

Upgrade Loris 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 loris
dpkg -s loris | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux

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

SUSE / openSUSE

sudo zypper refresh
sudo zypper update loris
rpm -q loris

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2026-26984 affecting Loris
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-26984-fix-$(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"
    $pkg = Get-Package -Name "*Loris*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "Loris" --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 "Loris"
    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-2026-26984 affecting Loris
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-26984-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 loris 2>/dev/null | grep -i ^Version || echo "loris not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q loris || echo "loris not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-26984-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/loris /etc/loris.d /etc/loris.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 loris
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y loris
elif command -v yum >/dev/null; then
    yum update -y loris
elif command -v zypper >/dev/null; then
    zypper --non-interactive update loris
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s loris 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q loris
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-2026-26984" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-26984"

Disable the affected service (Linux)

sudo systemctl stop loris 2>/dev/null || true
sudo systemctl disable loris 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 loris 2>/dev/null | grep -i ^Version
rpm -q loris 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 "*Loris*" | 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-2026-22323: Cross‑Site Request Forgery in Link Aggregation Configuration — Cross‑Site Request Forgery in Link Aggregation Configuration
• How to Fix CVE-2026-45207: Critical Vulnerability in TrendAI Apex One — Critical Vulnerability in TrendAI Apex One
• How to Fix CVE-2026-0743: Critical Vulnerability in WP Content Permission , Critical Vulnerability in WP Content Permission
• How to Fix CVE-2026-8381: Missing Authorization in DEX (On-premises) , Missing Authorization in DEX (On-premises)
• How to Fix CVE-2026-42155: Critical Vulnerability in magento-lts , Critical Vulnerability in magento-lts

Is CVE-2026-26984 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-2026-26984?

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-2026-26984?

8.7 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N.

Where is the official advisory for CVE-2026-26984?

The vendor advisory is at https://github.com/aces/Loris/security/advisories/GHSA-mpgc-c48m-6v2h. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-26984.

References

• Official vendor advisory: https://github.com/aces/Loris/security/advisories/GHSA-mpgc-c48m-6v2h
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-26984
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Additional reference: https://github.com/aces/Loris/releases/tag/v26.0.5
• Additional reference: https://github.com/aces/Loris/releases/tag/v27.0.2

*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.*