CVE-2026-73316 XenForo < 2.3.13 Payment Replay via PayPal REST Payment Provider
Attackers can replay PayPal webhooks to trigger duplicate payments, resulting in unauthorized account upgrades and repeated subscription activations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-73316?
CVE-2026-73316 is a high-severity vulnerability in XenForo, published on 8 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-345
Which versions are affected by CVE-2026-73316?
It affects 1 product.
Products include Xenforo Xenforo.
How do I fix CVE-2026-73316?
No fix has been published for CVE-2026-73316 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-73316 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73316 exists.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in XenForo
- CVE-2025-71279 XenForo Passkey Security Bypass
- CVE-2026-73309 XenForo < 2.3.13 Authentication Bypass via OAuth2 Token Endpoint
- CVE-2026-73311 XenForo < 2.3.13 OAuth2 Authorization Code Reuse
- CVE-2026-73312 XenForo < 2.3.13 Refresh Token Replay via Expired Access Token
- CVE-2024-38457 Xenforo before 2.2.16 allows CSRF.
Sources
Also known as GHSA-xc22-88fm-2h5f.