CVE-2026-4431: Auth Bypass (CVSS 9.1)

Description

The Easy Post Submission plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `create_post()` function in all versions up to, and including, 2.3.0. This is due to the `rbsm_submit_post` AJAX action being registered for unauthenticated users via `wp_ajax_nopriv_rbsm_submit_post` without any authorization checks when a `postId` parameter is supplied. This makes it possible for unauthenticated attackers to modify the title, content, excerpt, categories, and tags of arbitrary posts, as well as change the post status to draft (effectively unpublishing them) via the 'postId' parameter.

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CVSS v3.1 Score

9.1

CRITICAL

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

EPSS — Exploit Prediction

0.0033

Probability of exploitation

0.26%

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-862 Missing Authorization

References

Other References

https://plugins.trac.wordpress.org/browser/easy-post-submission/tags/2.2.0/includes/client-ajax-handler.php#L1157 https://plugins.trac.wordpress.org/browser/easy-post-submission/tags/2.2.0/includes/client-ajax-handler.php#L38 https://plugins.trac.wordpress.org/browser/easy-post-submission/tags/2.2.0/includes/client-ajax-handler.php#L974 https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&new=3488045%40easy-post-submission%2Ftrunk&old=3427523%40easy-post-submission%2Ftrunk https://www.wordfence.com/threat-intel/vulnerabilities/id/15494ccf-7c9d-4566-9e80-2da94172a3dd?source=cve

Frequently Asked Questions

What is CVE-2026-4431? +

The Easy Post Submission plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `create_post()` function in all versions up to, and including, 2.3.0. This is due to the `rbsm_submit_post` AJAX action being registered for unauthenticated users via `wp_ajax_nopriv_rbsm_submit_post` without any authorization checks when a `postId` parameter is supplied. This makes it possible for unauthenticated attackers to modify the title, content, excerpt, categories, and tags of arbitrary posts, as well as change the post status to draft (effectively unpublishing them) via the 'postId' parameter. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-4431? +

CVE-2026-4431 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0033, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-4431? +

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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