# CVE-2026-72728: Discourse: Onebox iframe origin allowlist enforces URL authority boundary

> Authenticated users can bypass Onebox iframe origin allowlists to embed malicious content, potentially leading to code execution.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 10 Aug 2026
- **Also known as:** BIT-discourse-2026-72728, GHSA-qp9j-3v7r-wrvr

## What is CVE-2026-72728?

CVE-2026-72728 is a medium-severity vulnerability in discourse, published on 10 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Discourse is an open-source discussion platform. Prior to 2026.1.7, an authenticated user could submit specially formed URLs that bypassed the Onebox allowlist and embedded malicious content in a site. This issue is fixed in versions 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0-latest.1.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-72728?

1 open source package ship an affected version, including discourse.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `discourse` | Bitnami | All versions | 2026.1.7, 2026.6.2, 2026.7.1 |

## How do I fix CVE-2026-72728?

Upgrade discourse to a fixed version for your release line: 2026.1.7, 2026.6.2 or 2026.7.1.

## Is CVE-2026-72728 being exploited?

There is no known exploitation of CVE-2026-72728 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72728 and fix it if it is affected.

What it is: CVE-2026-72728 is a medium-severity vulnerability in discourse, published on 10 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72728 in the wild and no public exploit code.

Affected packages and fixed versions:
- discourse (Bitnami): affected all versions; fixed in 2026.1.7, 2026.6.2, 2026.7.1

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-2026-72728/ (Markdown: https://insights.sbomify.com/CVE-2026-72728/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72728
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72728
- OSV: https://osv.dev/vulnerability/CVE-2026-72728

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72728/
Summaries are generated and may contain mistakes; the official description above is the record.