Privilege escalation in Simple Membership

CVE-2026-88764

The Simple Membership WordPress plugin before 4.7.8 does not validate that the membership level supplied in a PayPal payment notification matches the level configured for the paid payment button, allowing members to pay for a lower-priced membership while being granted a higher, more privileged membership level.

Vulnerability class: Privilege Escalation

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 13.8% 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-2026-88764: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

  • Simple Membership

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-88764?
CVE-2026-88764 is a medium-severity vulnerability in Simple Membership, classified under Improper Privilege Management. CVSS score: 5.4/10. Published 2026-09-13.
How severe is CVE-2026-88764?
Medium severity. CVSS v3 base score is 5.4 out of 10.