CVE-2026-27491 Discourse has a bypass of official warnings messages by non-staff users
Non-staff users can bypass authorization checks to issue official warnings to other users via a crafted API request.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27491?
CVE-2026-27491 is a medium-severity missing authorization vulnerability in Discourse Discourse, published on 19 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, a type coercion issue in a post actions API endpoint allowed non-staff users to issue warnings to other users. Warnings are a staff-only moderation feature. The vulnerability required the attacker to be a logged-in user and to send a specifically crafted request. No data exposure or privilege escalation beyond the ability to create unauthorized user warnings was possible. 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-2026-27491?
1 open source package ship an affected version, including discourse. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
discourse Bitnami | From 2026.1.0 | 2026.1.2, 2026.2.1, 2026.3.0 |
Products include Discourse Discourse.
How do I fix CVE-2026-27491?
Upgrade discourse to a fixed version for your release line: 2026.1.2, 2026.2.1 or 2026.3.0.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-27491 being exploited?
There is no known exploitation of CVE-2026-27491 in the wild and no public exploit code.
Other vulnerabilities in Discourse Discourse
- CVE-2021-41163 RCE via malicious SNS subscription payload
- CVE-2022-36066 Discourse vulnerable to RCE via admins uploading maliciously zipped file
- CVE-2022-39356 Discourse user account takeover via email and invite link
- CVE-2023-22468 Discourse vulnerable to Cross-site Scripting in local oneboxes
- CVE-2026-27934 Discourse leaks private topic title and post excerpt via user action API endpoint
Sources
Also known as BIT-discourse-2026-27491, GHSA-xq37-5fvf-4m4j.