# CVE-2026-33410: Discourse hardens chat DM channel creation and expansion

> Authenticated users can leak private group member identities and access DM channels of chat-disabled users due to missing authorization checks.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/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:** 19 Mar 2026
- **Updated:** 20 Mar 2026
- **Also known as:** BIT-discourse-2026-33410, GHSA-2m5j-6v2r-cq2h

## What is CVE-2026-33410?

CVE-2026-33410 is a medium-severity missing authorization vulnerability in Discourse Discourse, published on 19 Mar 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. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have two authorization issues in the chat direct message API. First, when creating a direct message channel or adding users to an existing one, the `target_groups` parameter was passed directly to the user resolution query without checking group or member visibility for the acting user. An authenticated chat user could craft an API request with a known private/hidden group name and receive a channel containing that group's members, leaking their identities. Second, `can_chat?` only checked group membership, not the `chat_enabled` user preference. A chat-disabled user could create or query DM channels between other users via the direct messages API, potentially exposing private `last_message` content from the serialized channel response. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-33410?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `discourse` | Bitnami | From 2026.1.0 | 2026.1.2, 2026.2.1, 2026.3.0 |

Products: Discourse Discourse.

## How do I fix CVE-2026-33410?

Upgrade discourse to a fixed version for your release line: 2026.1.2, 2026.2.1 or 2026.3.0.

## Is CVE-2026-33410 being exploited?

There is no known exploitation of CVE-2026-33410 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-2026-33410 and fix it if it is affected.

What it is: CVE-2026-33410 is a medium-severity missing authorization vulnerability in Discourse Discourse, published on 19 Mar 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-2026-33410 in the wild and no public exploit code.

Affected packages and fixed versions:
- discourse (Bitnami): affected from 2026.1.0; fixed in 2026.1.2, 2026.2.1, 2026.3.0

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-2026-33410/ (Markdown: https://insights.sbomify.com/CVE-2026-33410/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33410
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33410
- OSV: https://osv.dev/vulnerability/CVE-2026-33410

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33410/
Summaries are generated and may contain mistakes; the official description above is the record.