Meta Box AIO - Security Vulnerability (CVE-2026-13355)

Q: Am I affected by this vulnerability?

You are affected if your site runs Meta Box AIO. No account is needed to exploit this, so a public site is reachable by anyone.

Q: How do I fix it?

Update Meta Box AIO to the latest available version. Where the vendor has not yet published a fix, remove or disable the plugin until they do. Until you can update, Unauthorised administrator detection in Hack Halt ProSecure contains this class of attack at the request layer.

Q: What can an attacker actually do?

This is a Privilege Escalation flaw. An attacker who exploits it can raise a low-privilege account, or none at all, to administrator.

CVE-2026-13355

Vulnerability CVE-2026-13355 PLUGIN meta-box-aio CRITICAL

The Meta Box AIO plugin for WordPress is vulnerable to Privilege Escalation to Administrator in versions up to, and including, 3.11.0. This is due to a chained flaw: the populate_via_query_string() function in the mb-frontend-submission component unconditionally overrides the form's target object_id from the GET parameter 'rwmb_frontend_field_object_id' without any authorization check, and Form::process() lacks the user_can_edit() check present in render(), allowing unauthenticated attackers to overwrite the post_content of any page with an arbitrary shortcode via wp_update_post(); the mb-user-profile component then directly trusts the 'role' and 'auto_login' shortcode attributes in the injected [mb_user_profile_register] shortcode with no role validation. This makes it possible for unauthenticated attackers to elevate their privileges to Administrator. The standalone plugins Meta Box Frontend Submission (in versions up to 4.5.6) and Meta Box User Profile (versions up to 3.11.0) are also affected.

CVE-2026-13355

CRITICAL CVSS 9.8 Published 2026-09-22 Updated 2026-09-22

AI Risk Critical (100/100) Active Exploit: No strong signal Published Exploit: No public exploit references Priority: P1 Immediate

Severity Band CRITICAL

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

Affected Components 1

Reference Links 3

AI Risk Engine Critical (100/100)

Exploitability Very High

Active Exploitation No strong signal

Published Exploit Status No public exploit references

Threat Timeline

2026-09-22 CVE published and first recorded in the threat feed.
2026-09-22 Record updated with latest vulnerability metadata.
2026-09-22 AI technical context refreshed for mitigation and impact guidance.
Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated just now

AI enriched just now (2026-09-22 20:41 UTC)

Technical Summary

Potential Impact

Severity is CRITICAL (CVSS 9.8). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as Very High based on remote code execution potential, low-bar exploit prerequisites.

Primary risk drivers: remote code execution potential, low-bar exploit prerequisites

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

AI risk score 100/100 (Critical, Very High) with priority P1 Immediate. Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

Meta Box AIO PLUGIN · meta-box-aio Affected: <= 4.5.6 Fixed version not specified

References

What to do about this

Patch immediately Serious, and reachable without meaningful privilege.

Fix it

Update Meta Box AIO to the latest available version.

Where the vendor has not published a fix yet, disable the plugin until they do.

Cannot update today? Unauthorised administrator detection in Hack Halt ProSecure blocks this class of attack before WordPress processes the request.

Alert when a new administrator appears or a role is escalated. Creating a hidden admin is the most common persistence step after a WordPress compromise.

Compare Hack Halt plans Start free

Not sure if you are affected?

Scan your site to see whether it runs Meta Box AIO, and at which version.

Free, no installation, no account. It reads what your site already publishes, then tells you which plugins carry known vulnerabilities and what to do about each one.

Scan my site free See what Hack Halt does

Am I affected by this vulnerability?