Urgent: GravityWP — Merge Tags (<= 1.4.4) Local File Inclusion (CVE-2025-49271) — What WordPress Site Owners Must Do Now

This advisory is written by Hong Kong–based WordPress security practitioners who handle real incidents daily. On 8 August 2025 a Local File Inclusion (LFI) vulnerability affecting the GravityWP — Merge Tags plugin was disclosed (CVE-2025-49271). The issue affects plugin versions <= 1.4.4 and is rated High (CVSS 7.5). A patched release (1.4.5) is available. Because this vulnerability can be trivially discovered and exploited by unauthenticated attackers, immediate action is required for production sites.

Executive summary

• Vulnerability: Local File Inclusion (LFI) in GravityWP — Merge Tags plugin
• Affected versions: ≤ 1.4.4
• Fixed in: 1.4.5
• CVE: CVE-2025-49271
• CVSS: 7.5 (High)
• Privileges required: None (unauthenticated)
• Impact: Disclosure of local files (including wp-config.php and other secrets), potential chaining to remote code execution depending on environment, possible database takeover if credentials are leaked
• Immediate actions: Update plugin to 1.4.5, apply temporary mitigations (disable plugin or block the vulnerable endpoint), scan for indicators of compromise, rotate credentials if compromise is suspected

Why this is urgent

Local File Inclusion allows an attacker to make the application include and reveal local files from the web server. In WordPress contexts, the most critical files include wp-config.php (database credentials), site configuration files, and other files that may contain secrets. Because this plugin endpoint is accessible to unauthenticated visitors, automated scanners will find and attempt to exploit vulnerable sites quickly — often within hours of public disclosure.

Timely patching and temporary mitigations are essential even for low-profile sites. Automated opportunistic attacks do not discriminate.

What is Local File Inclusion (LFI)? A quick primer

LFI occurs when an application accepts a filename or path from user input and uses it in an include/require operation without proper validation. Attackers can abuse this to read arbitrary files by supplying:

• Relative traversal sequences (../../../../etc/passwd)
• PHP input streams (e.g., php://filter/resource=path)
• Files under wp-content/uploads that may be writable

A successful LFI can return file contents in the HTTP response or be chained to other techniques. In WordPress, reading wp-config.php is particularly dangerous because it contains DB credentials and salts.

Technical overview of this GravityWP Merge Tags vulnerability

Key points (high level):

• An endpoint associated with merge tags accepted user-controlled input used to build an include path.
• Input validation and path normalization were insufficient — no strict whitelisting — enabling directory traversal and local file access.
• The function could be invoked by unauthenticated users (no login required).
• An attacker can cause the plugin to include and output local files, exposing secrets.

Attributes:

• Unauthenticated: yes
• Vector: HTTP request to a publicly accessible plugin endpoint
• Potential impact: Credential disclosure (DB user/password, salts), information leakage, and possible chaining to further compromise

Fixed behavior (in 1.4.5): strict validation/whitelisting for included resources and/or removal of dynamic include logic; improved path normalization and sanitization to prevent traversal and wrapper access.

How attackers will likely exploit this

• Automated scanning: Bots probe known plugin endpoints for traversal strings or include patterns.
• Mass exploitation: Public exploit patterns are used to retrieve wp-config.php or other sensitive files across many sites.
• Post-exploitation: If credentials are recovered, attackers may connect to the DB, create admin users, inject malicious options, or exfiltrate data.

Expect rapid, automated attempts. Treat this as an active production risk.

Immediate steps (what to do in the next hour)

1. Inventory
   • Identify sites using the GravityWP — Merge Tags plugin.
   • Confirm plugin version on each site. If not present, you are not affected by this plugin-specific vulnerability.
2. Update
   • Update the plugin to version 1.4.5 immediately on staging and production.
   • If you cannot update immediately (compatibility testing), proceed to the mitigations below before exposing the site publicly.
3. Temporary mitigation if you cannot upgrade immediately
   • Disable the plugin until you can upgrade (deactivate via WP dashboard or rename the plugin folder via SFTP).
   • If disabling is not possible, apply firewall rules or server-level filters blocking requests to the vulnerable endpoint and blocking traversal sequences (“../”) and suspicious stream wrappers (php://, data:).
   • Consider placing the site into maintenance mode while remediating.
4. Monitor & scan
   • Run a full site malware scan and inspect web server logs for suspicious requests to plugin endpoints, especially those containing traversal strings or requests that returned file contents.
   • Look for unexpected outbound connections or newly created admin users.
5. Rotate credentials (if you suspect compromise)
   • If logs indicate wp-config.php or other sensitive files were accessed, rotate database credentials immediately and update wp-config.php.
   • Rotate any API keys or secrets stored on the site.
6. Backup
   • Create a secure full backup before making changes. Keep offsite copies.

How to detect attempted exploitation (indicators of attack)

Review web server access logs and WordPress logs for:

• HTTP requests with “../” sequences in query parameters (directory traversal attempts).
• Requests to plugin-specific paths or endpoints that contain unexpected parameters.
• Responses containing recognizable configuration or system file contents.
• 200 responses with content containing strings like “DB_NAME”, “DB_USER”, “DB_PASSWORD”.
• Requests containing stream wrappers such as “php://filter” or “data:”.
• Sudden creation of new WordPress users or changes to admin options shortly after suspicious requests.

Quick check: grep for “../” and plugin slugs in your access.log files and investigate matching requests.

Practical mitigation rules (firewall / virtual patch ideas)

Below are generic defensive patterns you can enforce via server rules, mod_security, reverse proxy, or WAFs you manage. These are conservative patterns intended to reduce exploitation risk until a full patch is applied:

• Block directory traversal: deny requests where parameter values contain “../” or “..\”.
• Block stream wrapper usage: deny requests containing “php://”, “data:”, “expect://”, “zip://” or “phar://”.
• Enforce allowed filenames: endpoints that should accept only a small set of resource names should whitelist allowable values.
• Block suspicious file extension access: deny requests attempting to include “.php” via controllable parameters or attempts to read files like wp-config.php, .env, /etc/passwd.
• Rate-limit or reject repetitive unauthenticated attempts to the plugin endpoint.
• Block obvious malicious user-agents and IPs exhibiting exploit behavior (use dynamic reputation feeds if available).

Apply mitigations carefully and test to avoid breaking legitimate functionality. These controls reduce exposure while you schedule the vendor patch.

Why updating is still the best long-term fix

Temporary filtering mitigations help, but the only complete fix is applying the vendor-supplied patch (1.4.5) that removes vulnerable logic or applies safe validation and whitelisting. An update addresses future edge cases that ad-hoc rules may miss and restores correct server-side validation.

Incident response if you find signs of compromise

1. Isolate
   • Put the site in maintenance mode or take it offline if feasible.
   • Temporarily restrict network access where possible.
2. Preserve evidence
   • Collect and secure web server logs, database logs, and WordPress logs for forensic analysis.
   • Make full backups of filesystem and database for investigators.
3. Eradicate
   • Remove web shells, unauthorized admin users, suspicious files, or cron jobs.
   • Reinstall the plugin from a clean source after upgrading to the fixed version.
   • Replace modified core files with known-good WordPress copies.
4. Restore secrets and credentials
   • Rotate database username/password.
   • Rotate API keys, third-party credentials, and WordPress salts.
   • Change admin passwords and enforce MFA where supported.
5. Rebuild trust
   • Run a full malware scan and validate clean state.
   • Confirm with your hosting provider whether any server-level compromise occurred.
   • Notify affected parties if data exfiltration occurred, according to applicable law and policy.
6. Post-incident learning
   • Document attack vector and timeline.
   • Update hardening checklist: file permissions, plugin removal policy, firewall coverage, backup cadence.
   • Schedule security review and improve monitoring/alerting.

If you are not confident handling a compromise, engage a trusted incident response provider or an experienced security consultant promptly.

Developer guidance — how to fix and avoid similar bugs

If you develop WordPress plugins, this class of vulnerability is preventable. Secure-coding recommendations:

• Whitelist, don’t blacklist: map valid keys to internal file paths; never directly include user-supplied filenames.
• Avoid dynamic includes: use switch/case or mapping to functions/templates rather than assembling file paths from input.
• Path normalization and safe checks: use realpath and verify the resolved path is inside an allowed directory.
• Disable file wrapper use: reject input containing “php://”, “data:”, etc.
• Capability checks and nonces: require appropriate capabilities (current_user_can) and nonces (wp_verify_nonce) where trust is required.
• Least privilege file permissions: keep writable directories isolated and avoid making plugin files writable by the web server when unnecessary.
• Code review and static analysis: run SAST tools and include security checks in reviews.
• Fuzz and penetration test endpoints: validate behavior against unexpected inputs.

Example safe pattern (conceptual):

$allowed_templates = [
  'email_header' => 'templates/email/header.php',
  'email_footer' => 'templates/email/footer.php',
];

$requested = $_GET['template'] ?? '';

if (!isset($allowed_templates[$requested])) {
  // handle invalid request
  wp_die('Invalid template', 400);
}

include plugin_dir_path(__FILE__) . $allowed_templates[$requested];

This mapping approach eliminates arbitrary file inclusion because only known keys map to fixed files.

Hardening checklist for WordPress site owners

• Update the vulnerable plugin to 1.4.5 immediately.
• If you cannot update immediately, disable the plugin until you can or apply server-side rules blocking traversal and stream wrappers.
• Run regular malware scans and integrity checks (compare files to clean plugin sources).
• Restrict file permissions (avoid world-writable plugin or core files).
• Harden PHP configuration:
  • disable allow_url_include = Off
  • disable unnecessary file uploads
  • use open_basedir restrictions where possible
• Keep backups and verify restore procedures.
• Enforce strong credentials and MFA for admin accounts.
• Monitor logs and set alerts for anomalous behaviour.

Disclosure and timeline (summary)

• Vulnerability reported: May 13, 2025 (researcher discovery)
• Public disclosure and increased exploit risk: August 2025
• Fixed version: 1.4.5
• CVE assigned: CVE-2025-49271

Because disclosures and patches often lead to automated exploitation, update immediately and apply temporary protections where possible.

Practical examples — what to look for in logs (sample patterns)

Defensive examples you may see in access logs:

• Directory traversal attempts:
  • GET /?tag=../../../../wp-config.php
  • GET /wp-content/plugins/merge-tags/?file=../../../../etc/passwd
• Stream wrapper attempts:
  • php://filter/convert.base64-encode/resource=wp-config.php
  • data://text/plain;base64,…
• Unexpected responses:
  • 200 OK responses with content containing “DB_NAME” or “DB_PASSWORD”
  • Files that look like configuration files returned by plugin pages

If you see these patterns, isolate the site and follow the incident response checklist above.

Communication advice for site owners and teams

• If you manage customers, notify them quickly about the vulnerability, the actions being taken (patch schedule, temporary mitigations), and any potential impact.
• Keep stakeholders informed of remediation progress and any evidence of compromise.
• Document the incident and post‑mortem actions to prevent recurrence.

Closing: simple priorities you should not skip

1. Check whether the GravityWP — Merge Tags plugin is installed and confirm the version.
2. If it’s ≤ 1.4.4, update to 1.4.5 immediately.
3. If you cannot update now, disable the plugin or apply server-side rules blocking traversal and stream wrappers.
4. Scan logs for evidence and rotate credentials if anything looks suspicious.
5. Ensure backups and incident response procedures are in place; rotate secrets as needed.

If you need assistance with virtual patching, log analysis, or emergency incident response, contact a trusted security consultant or an experienced incident response provider immediately. Rapid, correct action reduces the blast radius and cost of recovery.

Regards,
Hong Kong WordPress Security Practitioners