CVE-2026-33300 Discourse: Hidden group names and access metadata are exposed to moderators through the `category-chatables` endpoint

What is CVE-2026-33300?

CVE-2026-33300 is a medium-severity vulnerability in Discourse Discourse, published on 31 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. From versions 2026.1.0-latest to before 2026.1.3, 2026.2.0-latest to before 2026.2.2, and 2026.3.0-latest to before 2026.3.0, an authorization bypass in the Category Chatables Controller show action allowed moderators to get information on hidden groups names and user count. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.

Weakness: CWE-200

Which versions are affected by CVE-2026-33300?

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

Products include Discourse Discourse.

How do I fix CVE-2026-33300?

Upgrade discourse to a fixed version for your release line: 2026.1.3 or 2026.2.2.

Is CVE-2026-33300 being exploited?

There is no known exploitation of CVE-2026-33300 in the wild and no public exploit code.

Other vulnerabilities in Discourse Discourse

• CVE-2021-41163 RCE via malicious SNS subscription payload Critical 10.0
• CVE-2022-36066 Discourse vulnerable to RCE via admins uploading maliciously zipped file Critical 9.1
• CVE-2022-39356 Discourse user account takeover via email and invite link High 8.9
• CVE-2023-22468 Discourse vulnerable to Cross-site Scripting in local oneboxes High 8.8
• CVE-2026-27934 Discourse leaks private topic title and post excerpt via user action API endpoint High 8.7

All Discourse Discourse vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-discourse-2026-33300, GHSA-wrwm-vqx2-6x4v.