Vulnerability Details CVE-2026-73315
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 19.4%
CVSS Severity
CVSS v3 Score 8.6
References
- https://bombobombone.github.io/posts/cve-2026-73315/
- https://github.com/BomboBombone/CVE-2026-73315
- https://www.vulncheck.com/advisories/xenforo-ssrf-via-paypal-rest-webhook-handler
- https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/
- https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/