CVE-2026-11855 Simple Membership < 4.7.5 - Unauthenticated Stored XSS via Stripe Webhook API Version
Unauthenticated attackers can inject scripts via Stripe webhooks in Simple Membership plugin, leading to admin session hijacking.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-11855?
CVE-2026-11855 is a high-severity cross-site scripting vulnerability in Unknown Simple Membership, published on 6 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
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.
Which versions are affected by CVE-2026-11855?
How do I fix CVE-2026-11855?
No fix has been published for CVE-2026-11855 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-11855 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-11855 exists.
Sources
Also known as GHSA-xmqj-cv3v-f292.