CVE-2026-19807 ByteCoreStack <= 1.2.3 - Authenticated (Subscriber+) Privilege Escalation via wp_update_user_meta MCP Tool
Authenticated subscribers can escalate to Administrator by updating their own user meta capabilities via the MCP tool due to insufficient validation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-19807?
CVE-2026-19807 is a high-severity vulnerability in ByteCoreStack – MCP Connector for AI Tools, published on 1 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-269
Which versions are affected by CVE-2026-19807?
How do I fix CVE-2026-19807?
No fix has been published for CVE-2026-19807 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-19807 being exploited?
There is no known exploitation of CVE-2026-19807 in the wild and no public exploit code.
Sources
Also known as GHSA-qwvr-5fhh-47xh.