CVE-2026-6518
Published: 18 April 2026
Summary
CVE-2026-6518 is a high-severity Unrestricted Upload of File with Dangerous Type (CWE-434) vulnerability in Wordpress (inferred from references). Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 46.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-6 (Least Privilege) and CM-11 (User-installed Software).
Deeper analysis
CVE-2026-6518 is an arbitrary file upload vulnerability leading to remote code execution (RCE) in the CMP – Coming Soon & Maintenance Plugin by NiteoThemes for WordPress. All versions up to and including 4.1.16 are affected via the `cmp_theme_update_install` AJAX action. The flaw stems from the function checking only for the `publish_pages` capability, available to Editors and above, rather than the more restrictive `manage_options` required for Administrators. Additionally, there is no proper validation of the user-supplied file URL and no verification of the downloaded file's content before extraction, with a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) and mapped to CWE-434 (Unrestricted Upload of File with Dangerous Type).
Authenticated attackers with Administrator-level access can exploit this vulnerability over the network with low complexity. By supplying a malicious ZIP file URL under their control, they can force the WordPress server to download and extract the archive into the web-accessible directory `wp-content/plugins/cmp-premium-themes/`, enabling RCE. Editors possess the `publish_pages` capability but cannot exploit it due to the absence of a nonce verification for their role.
The WordPress plugin repository trac shows the patch introduced in version 4.1.17, with relevant code changes visible in lines around 1421, 1437, and 1447 of niteo-cmp.php, and the full changeset comparing tags 4.1.16 to 4.1.17. Wordfence's threat intelligence advisory provides further details on the vulnerability (https://www.wordfence.com/threat-intel/vulnerabilities/id/d6fb275b-dbba-46df-b170-977ef4a84c4c?source=cve). Security practitioners should update the plugin to 4.1.17 or later and review access to the `publish_pages` capability.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23654
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Arbitrary file upload in public-facing WordPress plugin allows malicious ZIP download/extraction to web dir for RCE, directly enabling T1190 (Exploit Public-Facing Application) and T1100 (Web Shell deployment).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly addresses the lack of proper validation on the user-supplied file URL and absence of verification of the downloaded file's content before extraction, preventing arbitrary malicious ZIP uploads.
Mitigates the insufficient access control by enforcing least privilege, requiring 'manage_options' capability for Administrators only instead of the overly permissive 'publish_pages' available to Editors.
Prohibits and scans user-supplied software like the malicious ZIP extracted into the web-accessible plugins directory, preventing unauthorized installation leading to RCE.