CVE-2026-109218: File Upload RCE (CVSS 9.8)

Description

The Contact Manager plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 9.1.2 via the add_message function. This is due to an incomplete extension blacklist that fails to detect dangerous extensions when a trailing dot causes the extension-derivation routine to return an empty string, which sanitize_file_name() then silently removes before the file is written to disk. This makes it possible for unauthenticated attackers to upload files that may be executable, which makes remote code execution possible. Successful code execution additionally requires the server to use Apache with libapache2-mod-php (which maps .phar to PHP by default) and the attacker to retrieve the uploaded file within the brief window before it is removed by unlink() at end of request.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0064

Probability of exploitation

0.51%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-434 Unrestricted Upload

References

Other References

https://fr.wordpress.org/plugins/contact-manager/ https://plugins.trac.wordpress.org/browser/contact-manager/tags/9.1.2/contact-manager.php#L42 https://plugins.trac.wordpress.org/browser/contact-manager/tags/9.1.2/includes/add-message.php#L254 https://plugins.trac.wordpress.org/browser/contact-manager/tags/9.1.2/includes/add-message.php#L256 https://plugins.trac.wordpress.org/browser/contact-manager/tags/9.1.2/includes/forms/processing.php#L102 https://plugins.trac.wordpress.org/changeset?reponame=&new=3767815%40contact-manager%2Ftags%2F9.1.3&old=3661172%40contact-manager%2Ftags%2F9.1.2 https://www.wordfence.com/threat-intel/vulnerabilities/id/b359ef59-4c2e-4d4e-b000-1845525131de?source=cve

Frequently Asked Questions

What is CVE-2026-109218? +

The Contact Manager plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 9.1.2 via the add_message function. This is due to an incomplete extension blacklist that fails to detect dangerous extensions when a trailing dot causes the extension-derivation routine to return an empty string, which sanitize_file_name() then silently removes before the file is written to disk. This makes it possible for unauthenticated attackers to upload files that may be executable, which makes remote code execution possible. Successful code execution additionally requires the server to use Apache with libapache2-mod-php (which maps .phar to PHP by default) and the attacker to retrieve the uploaded file within the brief window before it is removed by unlink() at end of request. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-109218? +

CVE-2026-109218 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0064, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-109218? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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