CVE-2026-26979 Discourse: TL4 users are able to change status of restricted topics

What is CVE-2026-26979?

CVE-2026-26979 is a missing authorization vulnerability in Discourse Discourse, published on 26 Feb 2026. An attacker needs administrator access to exploit it, with no action from the victim.

Official description

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, TL4 users are able to close, archive and pin topics in private categories they don't have access to. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

Weakness: CWE-862

Which versions are affected by CVE-2026-26979?

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

Products include Discourse Discourse.

How do I fix CVE-2026-26979?

Upgrade discourse to a fixed version for your release line: 2025.12.2 or 2026.1.1.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2026-26979 being exploited?

There is no known exploitation of CVE-2026-26979 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-2026-26979, GHSA-9c7p-fqc5-c24f.