CVE-2026-73315 XenForo < 2.3.13 SSRF via PayPal REST Webhook Handler

What is CVE-2026-73315?

CVE-2026-73315 is a high-severity server-side request forgery 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 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.

Weakness: CWE-918

Which versions are affected by CVE-2026-73315?

It affects 1 product.

Products include Xenforo Xenforo.

How do I fix CVE-2026-73315?

No fix has been published for CVE-2026-73315 yet. Limit exposure of the affected software until one is available.

Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.

Is CVE-2026-73315 being exploited?

There is no known exploitation of CVE-2026-73315 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Other vulnerabilities in XenForo

• CVE-2025-71279 XenForo Passkey Security Bypass Critical 9.3
• CVE-2026-73309 XenForo < 2.3.13 Authentication Bypass via OAuth2 Token Endpoint Critical 9.1
• CVE-2026-73311 XenForo < 2.3.13 OAuth2 Authorization Code Reuse Critical 9.1
• CVE-2026-73312 XenForo < 2.3.13 Refresh Token Replay via Expired Access Token Critical 9.1
• CVE-2024-38457 Xenforo before 2.2.16 allows CSRF. High 8.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-x4fx-w4wf-c38c.