● Medium · CVSS 6.5

How to Fix CVE-2026-2899: Missing authorization in Fluent Forms Pro Add On Pack

Q: What is the CVSS score for CVE-2026-2899?

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

Q: Where is the official advisory for CVE-2026-2899?

The vendor advisory is at [https://www.wordfence.com/threat-intel/vulnerabilities/id/bb036338-abd7-4061-835d-038b765c68a6?source=cve](https://www.wordfence.com/threat-intel/vulnerabilities/id/bb036338-abd7-4061-835d-038b765c68a6?source=cve). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-2899.

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

CVE-2026-2899 is a missing authorization in techjewel Fluent Forms Pro Add On Pack. The fix is to apply the vendor patch noted below.

⚡ At a glance

Severity	6.5 (Medium)
Actively exploited?	No public listing in CISA KEV
Affected	Fluent Forms Pro Add On Pack 0 to <=6.1.17
Fixed in	See vendor advisory
Type (CWE)	CWE-862 Missing Authorization

Exploitation status

As of this writing, CVE-2026-2899 does not appear on the CISA KEV catalog of actively-exploited flaws , no confirmed real-world exploitation has been catalogued by CISA. Do not read that as all-clear: the KEV catalog often trails real-world attacks, so prioritise this on its severity rather than waiting for a listing.

Public exploit availability: no public proof-of-concept or Metasploit module is referenced in this record yet. That says nothing about private exploit code, so do not treat the issue as low risk just because none is published.

What is CVE-2026-2899?

The Fluent Forms Pro Add On Pack plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 6.1.17. This is due to the deleteFile() method in the Uploader class lacking nonce verification and capability checks. The AJAX action is registered via addPublicAjaxAction() which creates both wp_ajax_ and wp_ajax_nopriv_ hooks. This makes it possible for unauthenticated attackers to delete arbitrary WordPress media attachments via the attachment_id parameter.

Note: The researcher described file deletion via the path parameter using sanitize_file_name(), but the actual code uses Protector::decrypt() for path-based deletion which prevents exploitation. The vulnerability is exploitable via the attachment_id parameter instead. The CVSS base score is 6.5 (Medium). The official advisory is at https://www.wordfence.com/threat-intel/vulnerabilities/id/bb036338-abd7-4061-835d-038b765c68a6?source=cve.

What you'll see

Check the version of Fluent Forms Pro Add On Pack you are running and compare it against the Affected row above (Fluent Forms Pro Add On Pack 0 to <=6.1.17). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:

# Linux package check
dpkg -s fluent-forms-pro-add-on-pack 2>/dev/null | grep -i ^Version
rpm -q fluent-forms-pro-add-on-pack 2>/dev/null
command -v fluent-forms-pro-add-on-pack >/dev/null && fluent-forms-pro-add-on-pack --version 2>/dev/null

# Windows (PowerShell)
Get-Package -Name "*Fluent Forms Pro Add On Pack*" -ErrorAction SilentlyContinue | Select-Object Name, Version
winget list --name "Fluent Forms Pro Add On Pack" 2>$null

How to fix CVE-2026-2899

Upgrade Fluent Forms Pro Add On Pack 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 fluent-forms-pro-add-on-pack
dpkg -s fluent-forms-pro-add-on-pack | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux

sudo dnf upgrade --refresh fluent-forms-pro-add-on-pack -y
# or for older releases:
sudo yum update fluent-forms-pro-add-on-pack -y
rpm -q fluent-forms-pro-add-on-pack

SUSE / openSUSE

sudo zypper refresh
sudo zypper update fluent-forms-pro-add-on-pack
rpm -q fluent-forms-pro-add-on-pack

PHP / Composer

composer update techjewel/fluent-forms-pro-add-on-pack 2>/dev/null || composer update
composer show | head -20

WordPress

# Update via WP-CLI
wp plugin update --all
wp core update

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2026-2899 affecting Fluent Forms Pro Add On Pack
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-2899-fix-$(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"
    $pkg = Get-Package -Name "*Fluent Forms Pro Add On Pack*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

    Write-Host "[2/4] Backup configuration"
    $backup = "C:\Backup\fluent-forms-pro-add-on-pack-$(Get-Date -Format yyyyMMdd)"
    New-Item -ItemType Directory -Force $backup | Out-Null
    Get-ChildItem "C:\ProgramData\Fluent Forms Pro Add On Pack" -ErrorAction SilentlyContinue |
        Copy-Item -Destination $backup -Recurse -Force -ErrorAction SilentlyContinue

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "Fluent Forms Pro Add On Pack" --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 "Fluent Forms Pro Add On Pack"
    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-2026-2899 affecting Fluent Forms Pro Add On Pack
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-2899-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 fluent-forms-pro-add-on-pack 2>/dev/null | grep -i ^Version || echo "fluent-forms-pro-add-on-pack not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q fluent-forms-pro-add-on-pack || echo "fluent-forms-pro-add-on-pack not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-2899-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/fluent-forms-pro-add-on-pack /etc/fluent-forms-pro-add-on-pack.d /etc/fluent-forms-pro-add-on-pack.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 fluent-forms-pro-add-on-pack
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y fluent-forms-pro-add-on-pack
elif command -v yum >/dev/null; then
    yum update -y fluent-forms-pro-add-on-pack
elif command -v zypper >/dev/null; then
    zypper --non-interactive update fluent-forms-pro-add-on-pack
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s fluent-forms-pro-add-on-pack 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q fluent-forms-pro-add-on-pack
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-2026-2899" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-2899"

Disable the affected service (Linux)

sudo systemctl stop fluent-forms-pro-add-on-pack 2>/dev/null || true
sudo systemctl disable fluent-forms-pro-add-on-pack 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.

The repair

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 fluent-forms-pro-add-on-pack 2>/dev/null | grep -i ^Version
rpm -q fluent-forms-pro-add-on-pack 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 "*Fluent Forms Pro Add On Pack*" | 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.

Other defects in the same area that deserve attention during this patch cycle:

Is CVE-2026-2899 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-2026-2899?

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-2026-2899?

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

Where is the official advisory for CVE-2026-2899?

The vendor advisory is at https://www.wordfence.com/threat-intel/vulnerabilities/id/bb036338-abd7-4061-835d-038b765c68a6?source=cve. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-2899.

References

Official vendor advisory: https://www.wordfence.com/threat-intel/vulnerabilities/id/bb036338-abd7-4061-835d-038b765c68a6?source=cve
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2899
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Additional reference: https://fluentforms.com/docs/changelog/#3-toc-title

Written by Sai Kiran Pandrala on 2026-05-25. Always confirm against the vendor's advisory before applying changes in production.