ByteCoreStack <= 1.2.3 — Authenticated (Subscriber+) Privilege Escalation via wp_update_user_meta MCP Tool

Am I affected?

• Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under ByteCoreStack – MCP Connector for AI Tools.
• No admin access? Run a passive check of your site. It reads public files only.

What to do

1. Update to version 1.2.4, or a newer patched version
2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
3. Watch ByteCoreStack – MCP Connector for AI Tools to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Décio Brandão.

The ByteCoreStack – MCP Connector for AI Tools plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 1.2.3 This is due to the `wp_update_user_meta` MCP tool in `execute_tool` gating writes solely with `current_user_can('edit_user', $uid)` — a check that WordPress core's `map_meta_cap` resolves to the `read` primitive when the target user ID matches the caller's own — while enforcing an incomplete meta key blocklist that covers only `user_pass`, `user_activation_key`, and `session_tokens`, leaving the `wp_capabilities` and `wp_user_level` meta keys entirely unprotected. This makes it possible for authenticated attackers with Subscriber-level access and above to elevate their privileges to Administrator by issuing a `wp_update_user_meta` call over the MCP JSON-RPC endpoint with `key=wp_capabilities` and an arbitrary role array such as `{'administrator': true}` targeting their own user ID, causing WordPress to load that account as an Administrator on the next request.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

• Advisorywordfence.com

Related CVEs

Timeline

1. Sep 30, 2026

   CVE published

   Severity high, CVSS 8.8

2. Nov 13, 2026

   Record last updated