CVE-2026-11855: Unknown Simple Membership

High severity, CVSS 8.8. EPSS: 0.5% chance of exploitation in the next 30 days.

The Simple Membership WordPress plugin before 4.7.5 does not verify the authenticity of Stripe webhook requests when no signing secret is configured, nor escape a value taken from them before outputting it in an administrator notice, allowing unauthenticated attackers to inject arbitrary web scripts that execute in the context of a logged-in administrator.

Affected products

• Unknown Simple Membership: before 4.7.5 (fixed in 4.7.5)

Published 2026-07-06. Last modified 2026-07-06.