Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-13355 – Unauthenticated Privilege Escalation to Administrator – Meta Box AIO ≤ 3.11.0 / MB

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-13355 is a critical unauthenticated privilege escalation vulnerability affecting the Meta Box AIO WordPress plugin bundle, along with its MB Frontend Submission and MB User Profile extensions. A chained flaw allows an unauthenticated attacker to inject a malicious shortcode into page content and then abuse it to create or elevate a user account to Administrator. The issue carries a CVSS v3.1 base score of 9.8 (Critical).

Technical details

  • Root cause: the populate_via_query_string() function in MB Frontend Submission overrides the form’s target object ID from the attacker-supplied rwmb_frontend_field_object_id GET parameter without any authorization check.
  • This is compounded by a missing user-capability check in Form::process(), which lets the request proceed and write attacker-controlled content into a page/post.
  • The injected content can contain the [mb_user_profile_register] shortcode from the MB User Profile extension, which trusts shortcode attributes (including a role attribute) without validating the requester’s permissions.
  • Attack vector: fully remote and unauthenticated — an attacker sends a crafted GET request to any page hosting a frontend submission form.
  • Impact: full compromise of the WordPress site via creation of, or escalation to, an Administrator-level account, leading to complete loss of confidentiality, integrity, and availability.

Affected software

  • Meta Box AIO: versions up to and including 3.11.0
  • MB Frontend Submission: versions up to and including 4.5.6
  • MB User Profile: versions up to and including 3.11.0

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical)
  • Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Immediate: Update Meta Box AIO, MB Frontend Submission, and MB User Profile to the latest versions released after this disclosure, which restore authorization checks in populate_via_query_string(), Form::process(), and the [mb_user_profile_register] shortcode handler.
  • If no patch is yet available for your version: disable or remove any frontend submission forms and the user-registration shortcode from public-facing pages until patched versions can be applied.
  • Review WordPress user accounts for unexpected Administrator-level users created after the vendor notification date (June 26, 2026).
  • Restrict or monitor requests containing the rwmb_frontend_field_object_id parameter at the web application firewall/edge layer as a temporary compensating control.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge