CVE-2026-18391 WooCommerce Subscriptions < 9.1.0 - Unauthenticated RCE via PHP Object Injection
Unauthenticated attackers can achieve remote code execution via PHP object injection in WooCommerce Subscriptions when High-Performance Order Storage is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18391?
CVE-2026-18391 is a critical unsafe deserialization vulnerability in Unknown WooCommerce Subscriptions, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-434
Which versions are affected by CVE-2026-18391?
How do I fix CVE-2026-18391?
No fix has been published for CVE-2026-18391 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-18391 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-18391 exists.
Sources
Also known as GHSA-5736-34m2-3cxc.