● Medium · CVSS 5.4

How to Fix CVE-2026-27411: Guessable captcha in SiteGuard WP Plugin

Q: What is the CVSS score for CVE-2026-27411?

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

Q: Where is the official advisory for CVE-2026-27411?

The vendor advisory is at [https://patchstack.com/database/Wordpress/Plugin/siteguard/vulnerability/wordpress-siteguard-wp-plugin-plugin-1-7-9-captcha-bypass-vulnerability?_s_id=cve](https://patchstack.com/database/Wordpress/Plugin/siteguard/vulnerability/wordpress-siteguard-wp-plugin-plugin-1-7-9-captcha-bypass-vulnerability?_s_id=cve). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27411.

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

CVE-2026-27411 is a guessable captcha in jp-secure SiteGuard WP Plugin. The fix is to upgrade to SiteGuard WP Plugin 1.7.10.

⚡ At a glance


Severity	5.4 (Medium)
Actively exploited?	No public listing in CISA KEV
Affected	SiteGuard WP Plugin 0 to <=1.7.9
Fixed in	SiteGuard WP Plugin 1.7.10
Type (CWE)	CWE-804: Guessable CAPTCHA

What is CVE-2026-27411?

Guessable CAPTCHA vulnerability in jp-secure SiteGuard WP Plugin siteguard allows Functionality Bypass.This issue affects SiteGuard WP Plugin: from n/a through <= 1.7.9. The CVSS base score is 5.4 (Medium). The official advisory is at https://patchstack.com/database/Wordpress/Plugin/siteguard/vulnerability/wordpress-siteguard-wp-plugin-plugin-1-7-9-captcha-bypass-vulnerability?_s_id=cve.

Am I affected?

Check the version of SiteGuard WP Plugin you are running and compare it against the Affected row above (SiteGuard WP Plugin 0 to <=1.7.9). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-27411

Upgrade SiteGuard WP Plugin to a patched build: SiteGuard WP Plugin 1.7.10. 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 siteguard-wp-plugin
dpkg -s siteguard-wp-plugin | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update siteguard-wp-plugin
rpm -q siteguard-wp-plugin

Node.js / npm


# Update the affected package in your project
npm install SiteGuard WP Plugin@latest
npm ls SiteGuard WP Plugin
npm audit fix

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-27411 affecting SiteGuard WP Plugin
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-27411-fix-$(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"
    $pkg = Get-Package -Name "*SiteGuard WP Plugin*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to SiteGuard WP Plugin 1.7.10"
    winget upgrade --name "SiteGuard WP Plugin" --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 "SiteGuard WP Plugin"
    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-2026-27411 affecting SiteGuard WP Plugin
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-27411-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 siteguard-wp-plugin 2>/dev/null | grep -i ^Version || echo "siteguard-wp-plugin not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q siteguard-wp-plugin || echo "siteguard-wp-plugin not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-27411-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/siteguard-wp-plugin /etc/siteguard-wp-plugin.d /etc/siteguard-wp-plugin.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: SiteGuard WP Plugin 1.7.10)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y siteguard-wp-plugin
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y siteguard-wp-plugin
elif command -v yum >/dev/null; then
    yum update -y siteguard-wp-plugin
elif command -v zypper >/dev/null; then
    zypper --non-interactive update siteguard-wp-plugin
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s siteguard-wp-plugin 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q siteguard-wp-plugin
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-2026-27411" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-27411"

Disable the affected service (Linux)


sudo systemctl stop siteguard-wp-plugin 2>/dev/null || true
sudo systemctl disable siteguard-wp-plugin 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 siteguard-wp-plugin 2>/dev/null | grep -i ^Version
rpm -q siteguard-wp-plugin 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 "*SiteGuard WP Plugin*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above SiteGuard WP Plugin 1.7.10. 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:

How to Fix CVE-2026-27472: Critical Vulnerability in SPIP — Critical Vulnerability in SPIP
How to Fix CVE-2026-33352: SQL Injection in AVideo — SQL Injection in AVideo
How to Fix CVE-2026-6475: Critical Vulnerability in PostgreSQL , Critical Vulnerability in PostgreSQL
How to Fix CVE-2026-5316: stb (Bundle Sibling) , stb (Bundle Sibling)
How to Fix CVE-2026-42279: Authorization Bypass Through User-Controlled Key in solidtime , Authorization Bypass Through User-Controlled Key in solidtime

Is CVE-2026-27411 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-2026-27411?

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-2026-27411?

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

Where is the official advisory for CVE-2026-27411?

The vendor advisory is at https://patchstack.com/database/Wordpress/Plugin/siteguard/vulnerability/wordpress-siteguard-wp-plugin-plugin-1-7-9-captcha-bypass-vulnerability?_s_id=cve. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27411.

References

Official vendor advisory: https://patchstack.com/database/Wordpress/Plugin/siteguard/vulnerability/wordpress-siteguard-wp-plugin-plugin-1-7-9-captcha-bypass-vulnerability?_s_id=cve
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27411
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

*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.*