What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-08 · updated 2026-09-11
• Weakness: CWE-918

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.

Affected products

• XenForo: before 2.3.13 — fixed in 2.3.13

How to fix

Upgrade to a fixed version: XenForo 2.3.13. Check the vendor advisory for mitigations.

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/

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