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

> Unauthenticated attackers can exploit a Server-Side Request Forgery in XenForo's PayPal webhook handler to access internal network resources and potentially disclose sensitive credentials.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-x4fx-w4wf-c38c

## 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 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-73315?

It affects 1 product.


Products: 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.

## 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:

- Sanitized XenForo write-up and proof of concept for CVE-2026-73315. (github_poc): https://github.com/BomboBombone/CVE-2026-73315

## Other vulnerabilities in XenForo

- [CVE-2025-71279](https://insights.sbomify.com/CVE-2025-71279/): XenForo Passkey Security Bypass (critical 9.3)
- [CVE-2026-73309](https://insights.sbomify.com/CVE-2026-73309/): XenForo < 2.3.13 Authentication Bypass via OAuth2 Token Endpoint (critical 9.1)
- [CVE-2026-73311](https://insights.sbomify.com/CVE-2026-73311/): XenForo < 2.3.13 OAuth2 Authorization Code Reuse (critical 9.1)
- [CVE-2026-73312](https://insights.sbomify.com/CVE-2026-73312/): XenForo < 2.3.13 Refresh Token Replay via Expired Access Token (critical 9.1)
- [CVE-2024-38457](https://insights.sbomify.com/CVE-2024-38457/): Xenforo before 2.2.16 allows CSRF. (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73315 and fix it if it is affected.

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

Affected product: XenForo. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-73315/ (Markdown: https://insights.sbomify.com/CVE-2026-73315/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73315
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73315
- OSV: https://osv.dev/vulnerability/CVE-2026-73315

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73315/
Summaries are generated and may contain mistakes; the official description above is the record.