CVE-2026-73316 [HIGH] – XenForo before 2.3.13 contains a payment replay vulnerability in the PayPal REST payment p

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.