Arbitrary file upload in Woocommerce Subscriptions

CVE-2026-18391

The WooCommerce Subscriptions WordPress plugin before 9.1.0 does not validate user input before unserializing it on stores with High-Performance Order Storage enabled, leading to a PHP Object Injection issue which unauthenticated users can escalate to Remote Code Execution via a gadget chain present in the bundled dependencies.

Vulnerability class: Unrestricted File Upload

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.010 (60.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 60th percentile — 60.1% 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-2026-18391: held from 0.006 to 0.010.

EPSS over last 30 days · oldest: 0.006 · newest: 0.010 · change: +0.004

Affected products

  • Woocommerce Subscriptions — versions 4.7.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-18391?
CVE-2026-18391 is a critical-severity vulnerability in Woocommerce Subscriptions, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2026-08-12.
How severe is CVE-2026-18391?
Critical severity. CVSS v3 base score is 9.8 out of 10.