Critical Vulnerability in WordPress Backup Plugin – CVE-2023-6553

Critical Vulnerability CVE-2023-6553

Bar Refael

December 12, 2023

A critical vulnerability, designated CVE-2023-6553, has been identified in the widely used WordPress plugin “Backup Migration,” impacting over 90,000 installations. This vulnerability poses a critical risk of 9.8 out of 10 and could allow an unauthenticated attacker to conduct remote code execution (RCE) attacks against an affected website. Despite timely patch releases, a significant number of websites remain vulnerable.

Vulnerability Details

  • Plugin: Backup Migration
  • Affected Versions: Up to and including 1.3.6
  • Vulnerability ID: CVE-2023-6553
  • Severity Score: 9.8/10 (Critical)
  • Discovery: Nex Team, reported via Wordfence’s bug bounty program
  • Impact: Remote Code Execution through PHP code injection

Technical Analysis

The vulnerability allows attackers to inject and execute arbitrary PHP code remotely. This is facilitated through the /includes/backup-heart.php file, where an attacker can manipulate the content-dir HTTP header to control the BMI_ROOT_DIR variable. This manipulation leads to the inclusion of malicious PHP code, granting attackers full control over the targeted WordPress site.

Mitigation Steps

  1. Immediate Update Required: WordPress site administrators must upgrade to the latest version of the Backup Migration plugin (1.3.8 or later).
  2. Verify Plugin Integrity: Ensure no unauthorized modifications have been made to the plugin files, especially /includes/backup-heart.php.
  3. Monitor for Suspicious Activity: Regularly check for signs of compromise or unusual activities on the website.
  4. Regularly Update All Plugins: Keep all WordPress plugins and the core system updated to prevent exploitation of known vulnerabilities.

Related Threats

  • Phishing Campaign: Concurrently, a phishing campaign is targeting WordPress administrators, luring them to install malicious plugins using fake security advisories.
  • Additional WordPress Vulnerability: A recent Property Oriented Programming (POP) chain vulnerability in WordPress could also lead to arbitrary PHP code execution in certain conditions.


The discovery of CVE-2023-6553 underscores the critical importance of timely updates and continuous security monitoring in the WordPress ecosystem. Given the high severity of this vulnerability and the active exploitation of WordPress sites, immediate action is required to secure potentially vulnerable sites and prevent potential compromises.

Recommendations for Administrators

  • Update the Backup Migration plugin immediately.
  • Stay vigilant against phishing attempts.
  • Regularly update and audit all WordPress components.
  • Monitor for unusual site behavior or unauthorized changes.

Intelligence Source Attribution

This CTI report is based on information provided by Wordfence and corroborated by subsequent security advisories and patch release details from BackupBliss, the developers behind Backup Migration.

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