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

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.006 (49.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-4431: held from 0.006 to 0.006.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

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.