dbcve.org
DiscourseApplication

CVE-2026-30891

MEDIUM · 6.5 CVSS v3.1 Published 2026-03-20
Fix available
A fix is available. Upgrade to 2026.1.2 / 2026.2.1 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, a user could access another user's private activity due to insufficient authorization checks in the user actions endpoint. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

This is an Insecure Direct Object Reference (IDOR) vulnerability in Discourse's user actions endpoint. An authenticated user could access another user's private activity due to missing or insufficient authorization checks, allowing unauthorized disclosure of private user data.

MitigationUpgrade Discourse to version 2026.3.0-latest.1, 2026.2.1, or 2026.1.2 to apply the patch that adds proper authorization validation to the user actions endpoint.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
DiscourseApplication
Affected:>= 2026.1.0, < 2026.1.2>= 2026.2.0, < 2026.2.1= 2026.3.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Discourse version
    Access the Discourse admin panel and navigate to /admin/about, or run `discourse version` from the command line if available. Alternatively, check the VERSION file in the Discourse installation directory if you have filesystem access.
    Affected if The installed version falls within any of these ranges: >= 2026.1.0 and < 2026.1.2, OR >= 2026.2.0 and < 2026.2.1, OR exactly 2026.3.0.
  2. Verify user actions feature is enabled
    In the Discourse admin panel, review the user preferences and site settings related to user activity and actions visibility. Check if users can view their own action history or if there are settings controlling activity feed visibility.
    Affected if The user actions or activity feed feature is enabled and accessible to authenticated users.
  3. Locate the user actions endpoint
    Identify the API endpoint responsible for retrieving user actions or activity. Common patterns include /user_actions, /activities, or similar REST endpoints under the /users path. Review your web server logs or Discourse routing configuration.
    Affected if The user actions endpoint exists and accepts user ID or username parameters without requiring admin-level authorization.
  4. Test authorization on the user actions endpoint
    Using an authenticated non-admin user account, attempt to access another user's private activity by manipulating the user_id or username parameter in the user actions API request. Observe whether private data from another user is returned.
    Affected if The endpoint returns private activity data from a different user than the authenticated requesting user, confirming the IDOR vulnerability.

You are affected if your Discourse version is 2026.1.0 through 2026.1.1, 2026.2.0, or exactly 2026.3.0 AND the user actions endpoint is accessible to authenticated users without proper cross-user authorization validation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2026.1.2 / 2026.2.1 or later
Fixed in 2026.1.22026.2.1
Interim mitigation

Upgrade Discourse to version 2026.3.0-latest.1, 2026.2.1, or 2026.1.2 to apply the patch that adds proper authorization validation to the user actions endpoint.

Recommended fix High confidence

2026.1.2, 2026.2.1, or 2026.3.0-latest.1 (or later)

  1. Identify your current Discourse version using the admin dashboard or by running `Discourse::VERSION::STRING` in the Rails console
  2. Backup your database and files before upgrading
  3. If running in a container/pod, pull the latest Docker image or update your deployment
  4. Upgrade to one of the fixed versions: 2026.1.2, 2026.2.1, or 2026.3.0-latest.1
  5. Restart the Discourse application after upgrade
  6. Verify the upgrade was successful by checking the version in the admin dashboard
  7. Log in as an admin and verify that the user actions endpoint now properly enforces authorization checks
Caveat Discourse minor version upgrades rarely introduce breaking changes, but always review release notes before upgrading and test in a staging environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Discourse Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-30891 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-30891 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data