# CVE-2026-72722: Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs

> Authenticated users can view titles of restricted topics via duplicate lookup responses, exposing private information.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N`)
- **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:** 13 Aug 2026
- **Also known as:** BIT-discourse-2026-72722, GHSA-4fx9-5m29-83p4

## What is CVE-2026-72722?

CVE-2026-72722 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 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-72722?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `discourse` | Bitnami | All versions | 2026.1.6, 2026.5.2, 2026.6.1 |

## How do I fix CVE-2026-72722?

Upgrade discourse to a fixed version for your release line: 2026.1.6, 2026.5.2 or 2026.6.1.

## Is CVE-2026-72722 being exploited?

There is no known exploitation of CVE-2026-72722 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72722 and fix it if it is affected.

What it is: CVE-2026-72722 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-2026-72722 in the wild and no public exploit code.

Affected packages and fixed versions:
- discourse (Bitnami): affected all versions; fixed in 2026.1.6, 2026.5.2, 2026.6.1

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-2026-72722/ (Markdown: https://insights.sbomify.com/CVE-2026-72722/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72722
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72722
- OSV: https://osv.dev/vulnerability/CVE-2026-72722

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72722/
Summaries are generated and may contain mistakes; the official description above is the record.