CVE-2026-33427 Discourse Authorization Page Displays Unvalidated Redirect Domain

What is CVE-2026-33427?

CVE-2026-33427 is a low-severity vulnerability in Discourse Discourse, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, an unauthenticated attacker can cause a legitimate Discourse authorization page to display an attacker-controlled domain, facilitating social engineering attacks against users. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Weakness: CWE-862

Which versions are affected by CVE-2026-33427?

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

Products include Discourse Discourse.

How do I fix CVE-2026-33427?

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

Is CVE-2026-33427 being exploited?

There is no known exploitation of CVE-2026-33427 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-2026-33427, GHSA-9vhg-2mx3-mqfr.