CVE-2026-73315: Xenforo

High severity, CVSS 8.6. EPSS: 0.4% chance of exploitation in the next 30 days.

XenForo before 2.3.13 contains a server-side request forgery vulnerability in the PayPal REST webhook handler that allows unauthenticated attackers to cause the server to make outbound HTTP requests to arbitrary destinations by supplying a crafted certificate URL in webhook headers without scheme, hostname, or allowlist validation. Attackers can submit a crafted POST to the PayPal webhook callback endpoint to reach internal network resources including cloud instance metadata services, potentially disclosing IAM credentials or enabling secondary internal service exploitation.

Affected products

• Xenforo Xenforo: before 2.3.13 (fixed in 2.3.13)

Published 2026-09-08. Last modified 2026-09-11.