Is CVE-2026-18391 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-18391 being exploited in the wild.

How severe is CVE-2026-18391?

Critical severity, with a CVSS score of 9.8, published 12 August 2026.

Which products and versions are affected?

WooCommerce Subscriptions before 9.1.0 (also affects 7.x before 7.9.1 and 8.x before 8.8.2).

Is there a fix for CVE-2026-18391?

A patch was published on 2026-08-12: Fixes released in 7.9.1, 8.8.2, and 9.1.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-18391 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-18391?

Check whether you run WooCommerce Subscriptions at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-18391: WooCommerce Subscriptions PHP Object Injection to RCE

CVE-2026-18391 · Severity: critical · CVSS 9.8 · Published 2026-08-12

WooCommerce Subscriptions is a popular WordPress plugin for managing subscription-based products on e-commerce stores. When High-Performance Order Storage is enabled, the plugin fails to validate user input before unserializing it, allowing unauthenticated attackers to execute arbitrary code on the server. This can lead to complete compromise of the online store, including theft of customer data and payment information.

Vendors: WooCommerce.

Quick answers

Is CVE-2026-18391 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-18391 being exploited in the wild.
How severe is CVE-2026-18391?: Critical severity, with a CVSS score of 9.8, published 12 August 2026.
Which products and versions are affected?: WooCommerce Subscriptions before 9.1.0 (also affects 7.x before 7.9.1 and 8.x before 8.8.2).
Is there a fix for CVE-2026-18391?: A patch was published on 2026-08-12: Fixes released in 7.9.1, 8.8.2, and 9.1.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-18391 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-18391?: Check whether you run WooCommerce Subscriptions at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is a PHP Object Injection (CWE-94) caused by unsafe deserialization of untrusted user input without validation. When High-Performance Order Storage is enabled in WooCommerce, the plugin processes attacker-controlled input through PHP's unserialize() function. An attacker can exploit gadget chains present in bundled dependencies to escalate this object injection into Remote Code Execution (RCE). The attack requires no authentication and is accessible over the network. The vulnerability affects versions before 9.1.0, with fixes released in versions 7.9.1, 8.8.2, and 9.1.0 depending on the release branch.

Affected products

WooCommerce Subscriptions before 9.1.0 (also affects 7.x before 7.9.1 and 8.x before 8.8.2)

Timeline

2026-08-10: disclosed
2026-08-12: advisory
2026-08-12: patched: Fixes released in 7.9.1, 8.8.2, and 9.1.0

References

https://wpscan.com/vulnerability/191f76cf-e5bd-4a37-ac1c-9187cea2aa27/

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