# CVE-2021-43792: Notifications leak in Discourse

> Revoked staff users may still receive notifications for restricted tags, leaking sensitive information to unauthorized users.

- **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:** 1 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** BIT-discourse-2021-43792, GHSA-pq2x-vq37-8522

## What is CVE-2021-43792?

CVE-2021-43792 is a medium-severity vulnerability in Discourse Discourse, published on 1 Dec 2021. 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. In affected versions a vulnerability affects users of tag groups who use the "Tags are visible only to the following groups" feature. A tag group may only allow a certain group (e.g. staff) to view certain tags. Users who were tracking or watching the tags via /preferences/tags, then have their staff status revoked will still see notifications related to the tag, but will not see the tag on each topic. This issue has been patched in stable version 2.7.11. Users are advised to upgrade as soon as possible.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2021-43792?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `discourse` | Bitnami | All versions | 2.7.11 |

Products: Discourse Discourse.

## How do I fix CVE-2021-43792?

Upgrade discourse to 2.7.11 or later.

## Is CVE-2021-43792 being exploited?

There is no known exploitation of CVE-2021-43792 in the wild and no public exploit code.

## Other vulnerabilities in Discourse Discourse

- [CVE-2021-41163](https://insights.sbomify.com/CVE-2021-41163/): RCE via malicious SNS subscription payload (critical 10.0)
- [CVE-2022-36066](https://insights.sbomify.com/CVE-2022-36066/): Discourse vulnerable to RCE via admins uploading maliciously zipped file (critical 9.1)
- [CVE-2022-39356](https://insights.sbomify.com/CVE-2022-39356/): Discourse user account takeover via email and invite link (high 8.9)
- [CVE-2023-22468](https://insights.sbomify.com/CVE-2023-22468/): Discourse vulnerable to Cross-site Scripting in local oneboxes (high 8.8)
- [CVE-2026-27934](https://insights.sbomify.com/CVE-2026-27934/): Discourse leaks private topic title and post excerpt via user action API endpoint (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43792 and fix it if it is affected.

What it is: CVE-2021-43792 is a medium-severity vulnerability in Discourse Discourse, published on 1 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43792 in the wild and no public exploit code.

Affected packages and fixed versions:
- discourse (Bitnami): affected all versions; fixed in 2.7.11

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-2021-43792/ (Markdown: https://insights.sbomify.com/CVE-2021-43792/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43792
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43792
- OSV: https://osv.dev/vulnerability/CVE-2021-43792

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43792/
Summaries are generated and may contain mistakes; the official description above is the record.