CVE-2026-1357

CVE-2026-1357 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 33% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-434.

Key facts

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.

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 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-1357 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 33% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-1357?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-1357 have an EU (EUVD) identifier?
Yes. CVE-2026-1357 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5948.
When was CVE-2026-1357 published?
CVE-2026-1357 was published on 2026-02-11 and last updated on 2026-06-17.

References

Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

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