by Kastro
Paper/Archive/CVE-2026-11964

CVE-2026-11964

Unknown User Registration & Membership — User Registration & Membership < 5.2.2 - Unauthenticated PayPal Webhook Signature Verification Bypass Leading to Membership Activation

EPSS 0.5%public exploitCVSS 9.1
critical.is priorityof 100
45
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 39.4.394 × 207.9Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

The User Registration & Membership WordPress plugin before 5.2.2 does not verify the authenticity of incoming payment-provider webhook notifications before acting on them, allowing unauthenticated attackers to forge a payment-approved event and activate a paid membership subscription without completing a real payment.

Affected

ProductAffectedFixed inSource
User Registration & Membership< 5.2.25.2.2CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

exploitwpscan.com/vulnerability/faf55649-8f76-4abf-a6b9-0d0774e22d29