Critical severity · published Jul 13, 2026
CVE-2026-11964
User Registration & Membership < 5.2.2 - Unauthenticated PayPal Webhook Signature Verification Bypass Leading to Membership Activation
9.1
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UR
User Registration & Membership ·
before 5.2.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-11964
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-11964
wpscan.com
https://wpscan.com/vulnerability/faf55649-8f76-4abf-a6b9-0d0774e22d29/
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