Vulnerability in Simple Membership

CVE-2026-11855

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (41.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 41.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-11855: held from 0.005 to 0.005.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

  • Simple Membership — versions 0

References

Frequently asked questions

What is CVE-2026-11855?
CVE-2026-11855 is a high-severity vulnerability in Simple Membership, classified under CWE-79 CROSS-SITE SCRIPTING (XSS). CVSS score: 8.8/10. Published 2026-07-06.
How severe is CVE-2026-11855?
High severity. CVSS v3 base score is 8.8 out of 10.