CVE-2026-1357

Comprehensive Technical Analysis of CVE-2026-1357

1. Vulnerability Assessment and Severity Evaluation

CVE ID: CVE-2026-1357 CVSS Score: 9.8

The vulnerability in the Migration, Backup, Staging – WPvivid Backup & Migration plugin for WordPress allows unauthenticated arbitrary file uploads due to improper error handling in the RSA decryption process and lack of path sanitization. This vulnerability is critical, as indicated by its high CVSS score of 9.8. The severity is attributed to the potential for remote code execution (RCE), which can lead to full system compromise.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Unauthenticated Arbitrary File Upload: An attacker can exploit the vulnerability without needing authentication.
• Directory Traversal: The lack of path sanitization allows an attacker to escape the protected backup directory and upload files to publicly accessible directories.

Exploitation Methods:

1. RSA Decryption Failure: The plugin fails to terminate execution upon RSA decryption failure, passing a boolean false value to the AES cipher initialization.
2. Predictable Null-Byte Key: The phpseclib library treats the false value as a string of null bytes, enabling an attacker to encrypt a malicious payload using a predictable key.
3. Unsanitized Filenames: The plugin accepts filenames from the decrypted payload without sanitization, allowing directory traversal.
4. Remote Code Execution: By uploading arbitrary PHP files, an attacker can achieve RCE via the wpvivid_action=send_to_site parameter.

3. Affected Systems and Software Versions

Affected Software:

• Migration, Backup, Staging – WPvivid Backup & Migration plugin for WordPress

Affected Versions:

• Versions up to and including 0.9.123

Platform:

• WordPress installations using the affected plugin versions

4. Recommended Mitigation Strategies

Immediate Actions:

1. Update the Plugin: Ensure that the WPvivid Backup & Migration plugin is updated to a version that addresses this vulnerability.
2. Disable the Plugin: If an update is not immediately available, consider disabling the plugin until a patched version is released.
3. Monitor for Suspicious Activity: Implement monitoring to detect any unusual file uploads or modifications in the WordPress directory.

Long-Term Mitigations:

1. Regular Updates: Maintain a regular update schedule for all plugins and WordPress core.
2. Security Plugins: Use security plugins like Wordfence to monitor and protect against vulnerabilities.
3. Access Controls: Implement strict access controls and authentication mechanisms to limit unauthorized access.
4. Code Review: Conduct thorough code reviews and security audits for plugins before deployment.

5. Impact on Cybersecurity Landscape

The discovery of CVE-2026-1357 highlights the importance of robust error handling and input validation in software development. The vulnerability underscores the potential risks associated with third-party plugins, particularly in widely-used platforms like WordPress. This incident serves as a reminder for organizations to prioritize regular security assessments and timely updates to mitigate such risks.

6. Technical Details for Security Professionals

Technical Overview:

• RSA Decryption Issue: The plugin uses openssl_private_decrypt() for RSA decryption. Upon failure, it does not terminate execution and passes a boolean false value to the AES cipher initialization.
• AES Cipher Initialization: The phpseclib library treats the false value as a string of null bytes, allowing an attacker to craft a predictable key.
• Directory Traversal: The plugin accepts unsanitized filenames from the decrypted payload, enabling directory traversal and arbitrary file uploads.

Code References:

• RSA Decryption Handling: class-wpvivid-crypt.php#L58
• File Upload Handling: class-wpvivid-send-to-site.php#L629

Exploitation Steps:

1. Craft Malicious Payload: Encrypt a malicious PHP file using a predictable null-byte key.
2. Upload Payload: Use the wpvivid_action=send_to_site parameter to upload the encrypted payload.
3. Achieve RCE: The uploaded PHP file can be executed to achieve remote code execution.

Detection and Response:

• Log Analysis: Review logs for unusual file uploads or modifications in the WordPress directory.
• File Integrity Monitoring: Implement file integrity monitoring to detect unauthorized changes.
• Intrusion Detection Systems (IDS): Deploy IDS to detect and alert on suspicious activities related to file uploads and RCE attempts.

By addressing these technical details and implementing the recommended mitigations, organizations can significantly reduce the risk posed by CVE-2026-1357 and similar vulnerabilities.