CVE-2026-6518

CMP – Coming Soon & Maintenance Plugin by NiteoThemes <= 4.1.16 - Missing Authorization to Authenticated (Administrator+) Arbitrary File Upload and Remote Code Execution

2026-04-17 15:02
Bao Le

Strategic Overview

Status
Patched in 4.1.17
Affected Version
<= 4.1.16
CVSS
8.8High
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE-2026-6518
View all CMP – Coming Soon & Maintenance Plugin by NiteoThemes vulnerabilities

At a glance

CVE-2026-6518 is a high-severity Unrestricted Upload of File with Dangerous Type vulnerability in the CMP WordPress plugin, affecting versions <= 4.1.16. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires an authenticated account at Administrator level or above. The issue is fixed in version 4.1.17; sites on affected versions should update now. Disclosed April 2026, reported by Bao Le.

Vulnerability Overview

The CMP – Coming Soon & Maintenance Plugin by NiteoThemes plugin for WordPress is vulnerable to arbitrary file upload and remote code execution in all versions up to, and including, 4.1.16 via the `cmp_theme_update_install` AJAX action. This is due to the function only checking for the `publish_pages` capability (available to Editors and above) instead of `manage_options` (Administrators only), combined with a lack of proper validation on the user-supplied file URL and no verification of the downloaded file's content before extraction. This makes it possible for authenticated attackers, with Administrator-level access and above, to force the server to download and extract a malicious ZIP file from a remote attacker-controlled URL into a web-accessible directory (`wp-content/plugins/cmp-premium-themes/`), resulting in remote code execution. Due to the lack of a nonce for Editors, they are unable to exploit this vulnerability.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-434: Unrestricted Upload of File with Dangerous Type

Reaching this weakness in CMP <= 4.1.16 takes an account at Administrator level or above. An unrestricted file upload lets a caller store a file whose type or destination the application does not properly constrain.

If an uploaded file lands anywhere the server will execute, the flaw becomes remote code execution and the site should be treated as fully compromised. For CMP the fix is 4.1.17: builds <= 4.1.16 are affected, anything from 4.1.17 onward is not.

Remediation

Update to version 4.1.17, or a newer patched version

How does WordSec protect against this?

An attacker needs Administrator access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: CMP 4.1.17 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Alerts

External References

Related records

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