CVE-2026-4139

Description

The mCatFilter plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to and including 0.5.2. This is due to the complete absence of nonce verification and capability checks in the compute_post() function, which processes settings updates. The compute_post() function is called in the plugin constructor on every page load via the plugins_loaded hook, and it directly processes $_POST data to modify plugin settings via update_option() without any CSRF token validation. This makes it possible for unauthenticated attackers to modify all plugin settings, including category exclusion rules, feed exclusion flags, and tag page exclusion flags, via a forged POST request, granted they can trick a site administrator into performing an action such as clicking a link.

CVSS v3.1 Score

4.3

MEDIUM

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.00%

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-352 Cross-Site Request Forgery

References

Other References

https://plugins.trac.wordpress.org/browser/mcatfilter/tags/0.5.2/mcatfilter.php#L138 https://plugins.trac.wordpress.org/browser/mcatfilter/tags/0.5.2/mcatfilter.php#L320 https://plugins.trac.wordpress.org/browser/mcatfilter/tags/0.5.2/mcatfilter.php#L339 https://plugins.trac.wordpress.org/browser/mcatfilter/trunk/mcatfilter.php#L138 https://plugins.trac.wordpress.org/browser/mcatfilter/trunk/mcatfilter.php#L320 https://plugins.trac.wordpress.org/browser/mcatfilter/trunk/mcatfilter.php#L339 https://www.wordfence.com/threat-intel/vulnerabilities/id/622ee6c8-7739-44ae-b88f-63a93c0a9b20?source=cve

Frequently Asked Questions

What is CVE-2026-4139? +

The mCatFilter plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to and including 0.5.2. This is due to the complete absence of nonce verification and capability checks in the compute_post() function, which processes settings updates. The compute_post() function is called in the plugin constructor on every page load via the plugins_loaded hook, and it directly processes $_POST data to modify plugin settings via update_option() without any CSRF token validation. This makes it possible for unauthenticated attackers to modify all plugin settings, including category exclusion rules, feed exclusion flags, and tag page exclusion flags, via a forged POST request, granted they can trick a site administrator into performing an action such as clicking a link. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-4139? +

CVE-2026-4139 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-4139? +

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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