CVE-2026-19807 PUBLISHED

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

Assigner: Wordfence
Reserved: 13.08.2026 Published: 01.10.2026 Updated: 01.10.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 8.8

Product Status

Vendor bytecorestack
Product ByteCoreStack – MCP Connector for AI Tools
Versions Default: unaffected
  • affected from 0 to 1.2.3 (incl.)

Credits

  • Décio Brandão finder

References

Problem Types

  • CWE-269 Improper Privilege Management CWE