# CVE-2026-4003: Privilege escalation in Users manager – PN

> Unauthenticated attackers can escalate privileges and take over accounts by updating arbitrary user metadata due to flawed authorization checks in the Users manager – PN plugin.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Apr 2026
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-f474-j5g7-2pch

## What is CVE-2026-4003?

CVE-2026-4003 is a critical vulnerability in felixmartinez Users manager – PN, published on 8 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Users manager – PN plugin for WordPress is vulnerable to Privilege Escalation via Arbitrary User Meta Update in all versions up to and including 1.1.15. This is due to a flawed authorization logic check in the userspn_ajax_nopriv_server() function within the 'userspn_form_save' case. The conditional only blocks unauthenticated users when the user_id is empty, but when a non-empty user_id is supplied, execution bypasses this check entirely and proceeds to update arbitrary user meta via update_user_meta() without any authentication or authorization verification. Additionally, the nonce required for this AJAX endpoint ('userspn-nonce') is exposed to all visitors via wp_localize_script on the public wp_enqueue_scripts hook, rendering the nonce check ineffective as a security control. This makes it possible for unauthenticated attackers to update arbitrary user metadata for any user account, including the userspn_secret_token field.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-4003?


## How do I fix CVE-2026-4003?

No fix has been published for CVE-2026-4003 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4003 being exploited?

There is no known exploitation of CVE-2026-4003 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4003 and fix it if it is affected.

What it is: CVE-2026-4003 is a critical vulnerability in felixmartinez Users manager – PN, published on 8 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-4003 in the wild and no public exploit code.

Affected product: felixmartinez Users manager – PN. 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-2026-4003/ (Markdown: https://insights.sbomify.com/CVE-2026-4003/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4003
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4003
- OSV: https://osv.dev/vulnerability/CVE-2026-4003

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4003/
Summaries are generated and may contain mistakes; the official description above is the record.