Auth bypass in Mstore API

CVE-2026-16039

The MStore API WordPress plugin before 4.21.0 does not restrict its vendor-orders endpoint to the caller's own orders, allowing any authenticated user, including Subscribers, to read every WooCommerce order in the store together with each customer's personal information.

Vulnerability class: IDOR (Insecure Direct Object Reference)

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:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.003 (27.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 27.6% 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-2026-16039: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

  • Mstore API — versions 0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-16039?
CVE-2026-16039 is a medium-severity vulnerability in Mstore API, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-08-07.
How severe is CVE-2026-16039?
Medium severity. CVSS v3 base score is 6.5 out of 10.