CVE-2026-73316: Xenforo

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

XenForo before 2.3.13 contains a payment replay vulnerability in the PayPal REST payment provider that allows attackers to process the same webhook payload multiple times by exploiting a missing duplicate transaction ID check. Attackers can replay a valid webhook payload to trigger duplicate payment events, resulting in repeated subscription activations and unauthorized account upgrades.

Affected products

• Xenforo Xenforo: before 2.3.13 (fixed in 2.3.13)

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