# CVE-2026-73319: XenForo < 2.3.13 XSS via Dynamic Redirect Handler

> Unauthenticated attackers can execute arbitrary JavaScript in authenticated users' browsers via a crafted redirect URI, potentially leading to account takeover.

- **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-vggm-cwh9-fm3v

## What is CVE-2026-73319?

CVE-2026-73319 is a medium-severity cross-site scripting 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 a cross-site scripting vulnerability in the dynamic redirect handler that allows unauthenticated attackers to execute arbitrary JavaScript in the board origin by crafting a malicious javascript: URI that bypasses host validation. Attackers can embed the board hostname in the URI authority component and use percent-encoded newlines to evade server-side filters, causing authenticated users who perform a Follow action to execute attacker-supplied JavaScript in their browser.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-73319?

It affects 1 product.


Products: Xenforo Xenforo.

## How do I fix CVE-2026-73319?

No fix has been published for CVE-2026-73319 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-73319 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73319 exists.

Public exploit code:

- Sanitized XenForo write-up and proof of concept for CVE-2026-73319. (github_poc): https://github.com/BomboBombone/CVE-2026-73319

## 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-2026-73319 and fix it if it is affected.

What it is: CVE-2026-73319 is a medium-severity cross-site scripting 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73319 exists.

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-2026-73319/ (Markdown: https://insights.sbomify.com/CVE-2026-73319/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73319
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73319
- OSV: https://osv.dev/vulnerability/CVE-2026-73319

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73319/
Summaries are generated and may contain mistakes; the official description above is the record.