Urgent: SQL Injection in MailArchiver Plugin (≤ 4.5.0) — What WordPress Site Owners Must Do Now

प्रकाशित: 26 February 2026

As a Hong Kong-based security professional, I’m issuing a concise, practical advisory for WordPress administrators and developers. A confirmed authenticated SQL injection (CVE-2026-2831) affects MailArchiver versions up to and including 4.5.0. The plugin author released a patch in 4.5.1. Read the steps below and act immediately if your site runs this plugin.

What this guide covers

• भेद्यता क्या है और यह क्यों महत्वपूर्ण है
• हमलावर इसे कैसे भुनाने के लिए सक्षम हो सकते हैं
• How to detect possible abuse
• Immediate mitigation and medium-term remediation
• Developer guidance for a correct fix
• WAF/virtual-patching guidance and incident-response checklist

Quick summary (essentials)

• कमजोरियों: Authenticated SQL Injection via logid parameter in MailArchiver (≤ 4.5.0).
• CVE: CVE-2026-2831
• आवश्यक विशेषाधिकार: प्रशासक
• Reported CVSS: 7.6 (high for injection risks when admin access is available)
• पैच किया गया संस्करण: 4.5.1 — update immediately where possible.

यह सुरक्षा दोष क्यों महत्वपूर्ण है

An SQL injection that requires Administrator access is still dangerous. In Hong Kong and globally, administrator accounts are prime targets for credential theft and social engineering. Once an admin is compromised, this vulnerability enables attackers to interact with the database directly.

• Read or modify arbitrary database records (users, options, posts).
• Persist backdoors, create new admin users, or exfiltrate sensitive data (emails, customer records).
• Chain post-exploitation steps to take over the site or pivot to other systems.

हमले के परिदृश्य - एक हमलावर क्या कर सकता है

1. Initial access: Attacker obtains admin credentials via credential stuffing, phishing, weak passwords, or an insider account.
2. Exploit via logid: A crafted logid value is injected into an insecure SQL query, allowing data read/modify operations.
3. पोस्ट-शोषण: Create admin accounts, inject backdoors, exfiltrate data, modify site content, or remove logs/backups.

किसे जोखिम है?

• Any WordPress site running MailArchiver ≤ 4.5.0.
• Sites with multiple administrators or shared admin credentials.
• Sites without strong logging, monitoring, or WAF protections.

अपने प्लगइन संस्करण की जांच करें

If unsure which version you run, check the plugin screen in WP admin or use WP-CLI:

# via WP-CLI
wp plugin list --path=/path/to/wordpress | grep mailarchiver

तात्कालिक क्रियाएँ (पहला घंटा)

Follow these steps in order. The top priority is to update or block exploitation paths.

1. Update MailArchiver to 4.5.1 immediately if possible: update via admin UI or WP-CLI (wp plugin update mailarchiver).
2. If you cannot update immediately (compatibility/testing), apply virtual patching/WAF controls to block unsafe logid मान।.
3. Rotate all administrator passwords and any service accounts with elevated permissions; enforce unique passwords and enable two-factor authentication (2FA).
4. Audit admin users for unknown accounts and remove or demote suspicious entries (wp उपयोगकर्ता सूची --भूमिका=प्रशासक).
5. Consider restricting admin access by IP or placing the site into maintenance mode temporarily.
6. Take a fresh backup (files + database) and store it offline — preserve for forensics if compromise is suspected.
7. Scan the site for malware and unauthorized changes using your security scanner.
8. Collect logs: webserver access/error logs, WordPress logs, plugin logs, and any available database logs.
9. If you find suspicious indicators, take the site offline and begin incident-response procedures immediately.

नोट: Updating to 4.5.1 is the single most important step. If that cannot be done immediately, virtual patching is the best interim mitigation.

शोषण का पता कैसे लगाएं

Indicators that SQL injection may have been used:

• SQL errors in webserver or WP debug logs.
• New or modified admin users.
• अप्रत्याशित परिवर्तन 11. संदिग्ध सामग्री के साथ।, hidden scripts in posts, or unknown rows in tables.
• Suspicious outgoing connections or data transfers.
• Modified plugin/theme files or PHP files under wp-content/uploads/.

Practical detection queries and checks

Review recent admin logins and suspicious activity. Examples:

# List administrators (WP-CLI)
wp user list --role=administrator --format=csv

# Find PHP files in uploads (common webshell location)
find wp-content/uploads -type f -name "*.php"

-- Search for suspicious option entries (SQL)
SELECT option_name, option_value, autoload
FROM wp_options
WHERE option_name LIKE '%custom%' OR option_name LIKE '%backdoor%' OR option_name LIKE '%_transient_%'
ORDER BY option_id DESC LIMIT 200;

Also search webserver/access logs for logid usage and suspicious tokens (union, select, –, /*, etc.). If clear evidence is found, isolate the site and perform a full incident response.

Short- and medium-term mitigations

अल्पकालिक (घंटे)

• Update MailArchiver to 4.5.1.
• Apply WAF rules to block unsafe logid मान।.
• Rotate admin passwords and enable 2FA.
• Restrict admin-area access by IP where feasible.
• Take a clean backup and preserve it offline for forensics.

Medium-term (days–weeks)

• Audit other plugins and themes for similar unsafe SQL practices.
• Adopt a staging-to-production update workflow and consider selective automatic updates.
• Harden WordPress: disable file editing, enforce secure file permissions, and review upload handling.
• Maintain continuous monitoring and tuned WAF rules that alert on DB-like payloads in parameters.
• Perform full malware and integrity scans across files and database.

Long-term (weeks–months)

• Apply least-privilege for accounts and services.
• Conduct regular security audits and penetration tests.
• Centralise logging and alerting for faster detection.
• Keep tested backups offsite and verify restore procedures.

WAF / आभासी पैचिंग मार्गदर्शन

If immediate plugin update is not possible, virtual patching via a WAF is a practical stopgap. Below are example rules and guidance. Always test in detection-only mode first to avoid blocking legitimate use.

उच्च-स्तरीय नियम लॉजिक

• Only allow logid values that match the expected format (typically numeric).
• अवरुद्ध करें logid values containing SQL metacharacters or keywords (UNION, SELECT, INFORMATION_SCHEMA, –, /*, ;, etc.).
• Monitor and alert on admin requests carrying logid with suspicious tokens.

उदाहरण ModSecurity-शैली नियम (चित्रात्मक)

# Block suspicious logid parameter inputs (tune for your environment)
SecRule REQUEST_URI|ARGS_NAMES|ARGS "logid" "phase:2,chain,deny,log,msg:'Block suspicious logid parameter - possible SQLi'
    SecRule ARGS:logid \"(?i:(union|select|information_schema|benchmark|sleep|--|;|/\*|\*/|char\(|concat\(|0x[0-9a-f]{2,}|having|group\s+by))\" \
    \"t:none,t:lowercase,logdata:'Matched logid SQLi pattern',severity:CRITICAL\"
"

Strict approach if logid is numeric

# Allow only digits in logid (detection-first)
SecRule ARGS:logid "@rx ^\d+$" "phase:2,pass,nolog,ctl:ruleEngine=DetectionOnly"
# If not digits, block (use detection mode initially)
SecRule ARGS:logid "@rx ^(?!\d+$)" "phase:2,deny,log,msg:'Blocked non-numeric logid - potential SQLi'"

महत्वपूर्ण नोट्स:

• Test rules in detection-only mode before denying traffic to avoid false positives.
• Tune for your environment — some sites may legitimately use non-numeric IDs.
• Log full request context for investigation (headers, body, IP).
• Use pattern-based blocking combined with behavioural analysis to reduce collisions with other plugins.

Developer guidance — how to fix it properly

Plugin authors must validate input, use parameterised queries, and check capabilities. The correct approach:

• Validate and sanitize all input.
• Use parameterised queries (in WP: $wpdb->prepare).
• जांचें current_user_can() for an appropriate capability before performing database operations.
• Cast numeric IDs with intval() या absint() when expecting integers.

Vulnerable pattern (example)

<?php
$logid = $_GET['logid'];
$sql = "SELECT * FROM {$wpdb->prefix}mail_logs WHERE id = $logid";
$results = $wpdb->get_results( $sql );
?>

Safe pattern (fixed)

<?php
if ( ! current_user_can( 'manage_options' ) ) {
    wp_die( 'Insufficient permissions' );
}

$logid = isset( $_GET['logid'] ) ? intval( $_GET['logid'] ) : 0; // cast to integer

$sql = $wpdb->prepare(
    "SELECT * FROM {$wpdb->prefix}mail_logs WHERE id = %d",
    $logid
);
$results = $wpdb->get_results( $sql );
?>

Key points: never interpolate user input directly into SQL. Use prepared statements and validate user capabilities.

घटना प्रतिक्रिया चेकलिस्ट (चरण-दर-चरण)

1. अलग करें: Restrict admin access by IP or enable maintenance mode. Temporarily disable the vulnerable plugin if safe.
2. संरक्षित करें: Snapshot files and database; store offline and mark for forensics. Preserve logs (web, error, DB).
3. पहचानें: Look for unknown admin users, new PHP files, modifications to plugins/themes, and outgoing connections.
4. सुधारें: Update plugin to 4.5.1 (or uninstall if not needed), rotate admin credentials and API keys, remove unknown admin users, and clean or restore from a verified backup.
5. पुनर्प्राप्त करें: Harden the site (disable file editors in WP, enforce permissions), re-enable services once confident and monitored.
6. सीखें: Conduct root-cause analysis, update patch workflows, and ensure backups and monitoring are tested.

If you lack internal resources for a full investigation, engage experienced incident responders or a reputable security provider.

Mitigation best practices to reduce future risk

• Enforce unique, strong admin passwords and enable 2FA for all admin accounts.
• Minimise the number of administrator accounts and apply least-privilege.
• Keep plugins and themes updated and test upgrades in staging first.
• Run scheduled integrity scans and file comparisons.
• Maintain regular, tested backups stored separately from the server.
• Centralise and monitor logs, and alert on anomalous admin actions or unusual database query patterns.

Example detection rules and log queries

Quick commands to search logs for suspicious logid उपयोग:

# Search access logs for requests with 'logid='
grep -i "logid=" /var/log/nginx/access.log* | tail -n 200

# Find requests containing possible SQL keywords
grep -i "logid=.*union\|select\|information_schema\|benchmark\|sleep" /var/log/nginx/access.log -n

Database queries to look for recent suspicious changes:

-- Recent admin users
SELECT user_login, user_email, user_registered
FROM wp_users
WHERE user_registered > DATE_SUB(NOW(), INTERVAL 14 DAY)
ORDER BY user_registered DESC;

-- Potential injected option names
SELECT option_id, option_name, option_value
FROM wp_options
WHERE option_name LIKE '%_tmp_%' OR option_name LIKE '%system_%'
ORDER BY option_id DESC LIMIT 100;

Why managed WAF and virtual patching matter

In production environments immediate code updates are not always feasible due to staging, compatibility testing, or change controls. Managed WAFs and virtual patching help by:

• Blocking exploitation attempts at the perimeter before they reach the application.
• Providing centralised logging and alerts for suspicious patterns across multiple sites.
• Reducing the exposure window while you perform code fixes and forensic checks.

Use virtual patching as a mitigation, not a replacement for fixing the underlying code.

Final checklist — what to do next

1. Check if MailArchiver is installed — update to 4.5.1 now.
2. If immediate update is not possible — implement WAF/virtual patch for the logid पैरामीटर।.
3. Rotate administrator credentials and enable 2FA.
4. Audit admin users and the filesystem for new/modified files.
5. Take a full backup and preserve logs for forensic review.
6. Harden the site with least-privilege, logging, backups, and scheduled testing.

If you require immediate help with containment, virtual patching, or recovery, engage an experienced incident-response team. Prioritise the plugin update first — that reduces the risk most quickly.