Auth bypass in Mstore API

CVE-2026-18233

The MStore API WordPress plugin before 4.21.1 does not verify that the order targeted by one of its delivery endpoints belongs to the requester, allowing any authenticated user, including Subscribers, to mark arbitrary orders as completed and paid without any payment being made.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.002 (5.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 5.8% 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-2026-18233: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: -0.000

Affected products

  • Mstore API

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-18233?
CVE-2026-18233 is a medium-severity vulnerability in Mstore API, classified under Missing Authorization. CVSS score: 6.5/10. Published 2026-08-29.
How severe is CVE-2026-18233?
Medium severity. CVSS v3 base score is 6.5 out of 10.