Unauthenticated RCE in a widely deployed WooCommerce plugin impacting many e‑commerce WordPress sites; high risk of store compromise and data theft.
CVE-2026-18391
Unauthenticated PHP object injection in WooCommerce Subscriptions permits RCE on HPOS-enabled stores.
Is CVE-2026-18391 being exploited?
Not confirmed. CVE-2026-18391 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.61% probability of exploitation in the next 30 days.
How severe is CVE-2026-18391?
CVE-2026-18391 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-18391?
Yes. A fix has been recorded for CVE-2026-18391. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-18391 affect?
CVE-2026-18391 affects WooCommerce Subscriptions < 9.1.0, WordPress stores using High-Performance Order Storage (HPOS), Sites using the plugin's bundled PHP dependencies. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-18391?
Upgrade WooCommerce Subscriptions to 9.1.0 immediately; disable HPOS or deploy WAF mitigations if upgrade delayed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attackers can trigger PHP object injection and achieve remote code execution on stores with High-Performance Order Storage enabled.
Immediate action required
- affected>= 4.7.0 and < 9.1.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.