CVE-2026-1357: The Migration, Backup, Staging – WPvivid Backup & Migration plugin for WordPress is vulnerable to Unauthenticated Arbitrary File Upload in versions up...

Description

The Migration, Backup, Staging – WPvivid Backup & Migration plugin for WordPress is vulnerable to Unauthenticated Arbitrary File Upload in versions up to and including 0.9.123. This is due to improper error handling in the RSA decryption process combined with a lack of path sanitization when writing uploaded files. When the plugin fails to decrypt a session key using openssl_private_decrypt(), it does not terminate execution and instead passes the boolean false value to the phpseclib library's AES cipher initialization. The library treats this false value as a string of null bytes, allowing an attacker to encrypt a malicious payload using a predictable null-byte key. Additionally, the plugin accepts filenames from the decrypted payload without sanitization, enabling directory traversal to escape the protected backup directory. This makes it possible for unauthenticated attackers to upload arbitrary PHP files to publicly accessible directories and achieve Remote Code Execution via the wpvivid_action=send_to_site parameter.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

32.71%

98.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-434

References

Timeline

Published: Feb 11, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-1357?

The Migration, Backup, Staging – WPvivid Backup & Migration plugin for WordPress is vulnerable to Unauthenticated Arbitrary File Upload in versions up to and including 0.9.123. This is due to improper error handling in the RSA decryption process combined with a lack of path sanitization when writing uploaded files. When the plugin fails to decrypt a session key using openssl_private_decrypt(), it does not terminate execution and instead passes the boolean false value to the phpseclib library's AES cipher initialization. The library treats this false value as a string of null bytes, allowing an attacker to encrypt a malicious payload using a predictable null-byte key. Additionally, the plugin accepts filenames from the decrypted payload without sanitization, enabling directory traversal to escape the protected backup directory. This makes it possible for unauthenticated attackers to upload arbitrary PHP files to publicly accessible directories and achieve Remote Code Execution via the wpvivid_action=send_to_site parameter.

How severe is CVE-2026-1357?

CVE-2026-1357 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 32.71% probability of exploitation in the next 30 days.

How do I fix CVE-2026-1357?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.