# 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.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Oct 2026
- **Updated:** 3 Oct 2026
- **Also known as:** GHSA-qwvr-5fhh-47xh

## 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 (Improper Privilege Management)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19807 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-19807 in the wild and no public exploit code.

Affected product: ByteCoreStack – MCP Connector for AI Tools. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-19807/ (Markdown: https://insights.sbomify.com/CVE-2026-19807/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19807
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19807
- OSV: https://osv.dev/vulnerability/CVE-2026-19807

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-19807/
Summaries are generated and may contain mistakes; the official description above is the record.