Auth bypass in Themeruby Easy Post Submission – Frontend Posting, Guest Publishing & Submit Content For WordPress

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.

Vulnerability class: Broken Access Control

EPSS: 0.003 (26.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-4431?
CVE-2026-4431 is a critical-severity vulnerability in Themeruby Easy Post Submission – Frontend Posting, Guest Publishing & Submit Content For WordPress, classified under Missing Authorization. CVSS score: 9.1/10. Published 2026-08-05.
How severe is CVE-2026-4431?
Critical severity. CVSS v3 base score is 9.1 out of 10.