# CVE-2026-73320: XenForo < 2.3.13 Unauthenticated Information Disclosure via Unfurl Endpoint

> Unauthenticated attackers can retrieve private unfurl records, including preview HTML and URLs, by enumerating predictable IDs in XenForo.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 8 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-5j56-975f-v5v8

## What is CVE-2026-73320?

CVE-2026-73320 is a medium-severity vulnerability in XenForo, published on 8 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

XenForo before 2.3.13 contains an unauthenticated information disclosure vulnerability that allows unauthenticated attackers to retrieve private unfurl records by supplying predictable auto-increment primary key IDs to the unfurl endpoint. Attackers can enumerate or predict result IDs and query the endpoint without any session, user, or visibility checks to obtain rendered preview HTML, original URLs, and query strings from private conversations and other restricted content.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-73320?

It affects 1 product.


Products: Xenforo Xenforo.

## How do I fix CVE-2026-73320?

No fix has been published for CVE-2026-73320 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-73320 being exploited?

There is no known exploitation of CVE-2026-73320 in the wild and no public exploit code.

Public exploit code:

- Sanitized XenForo write-up and proof of concept for CVE-2026-73320. (github_poc): https://github.com/BomboBombone/CVE-2026-73320

## 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-2026-73320 and fix it if it is affected.

What it is: CVE-2026-73320 is a medium-severity vulnerability in XenForo, published on 8 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-73320 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-2026-73320/ (Markdown: https://insights.sbomify.com/CVE-2026-73320/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73320
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73320
- OSV: https://osv.dev/vulnerability/CVE-2026-73320

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73320/
Summaries are generated and may contain mistakes; the official description above is the record.