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DiscourseApplication

CVE-2026-28218

MEDIUM · 5.4 CVSS v3.1 Published 2026-02-26
Fix available
A fix is available. Upgrade to 2025.12.2 / 2026.1.1 or later.
See remediation →
60/100
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 2025.12.2, 2026.1.1, and 2026.2.0, fail-open access control in Data Explorer plugin allows any authenticated user to execute SQL queries that have no explicit group assignments, including built-in system queries. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. As a workaround, either explicitly set group permissions on each Data Explorer query that doesn't have permissions, or disable discourse-data-explorer plugin.

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 · high confidence

Discourse's Data Explorer plugin has a fail-open access control vulnerability where SQL queries lacking explicit group permissions can be executed by any authenticated user, including built-in system queries that should be restricted.

MitigationUpgrade to Discourse versions 2025.12.2, 2026.1.1, or 2026.2.0 to patch the vulnerability, or alternatively explicitly assign group permissions to each Data Explorer query or disable the plugin entirely.

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:< 2025.12.2>= 2026.1.0, < 2026.1.1= 2026.2.0

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
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/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. Verify Data Explorer plugin is enabled
    Navigate to /admin/plugins or check the Discourse admin interface for installed plugins. Look for 'Data Explorer' in the list of active plugins.
    Affected if Data Explorer plugin is installed and enabled
  2. Check Discourse core version
    Run `git log -1 --format='%H %s'` in the Discourse container/folder, or check /admin/about in the Discourse admin panel, or inspect the VERSION file in the Discourse installation directory.
    Affected if Version is < 2025.12.2, OR >= 2026.1.0 AND < 2026.1.1, OR equals 2026.2.0
  3. List Data Explorer queries without group permissions
    Query the database: `SELECT id, name, created_at FROM data_explorer_queries WHERE group_ids IS NULL OR group_ids = '[]';` using Discourse's database console or rails runner.
    Affected if Any rows returned indicate queries lack explicit group permissions
  4. Verify built-in system queries are exposed
    Check if queries with names like 'deadliest attacks', 'spam', 'system' or query IDs 1-10 are accessible. Use the Data Explorer API endpoint `/admin/plugins/explorer/queries/{id}/run` with a low-privilege authenticated user account.
    Affected if A user without admin privileges can execute queries that should be restricted to admins or specific groups

The environment is affected if Data Explorer is enabled AND the Discourse version is within the affected ranges AND any Data Explorer queries lack group permissions, allowing unauthorized access.

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 2025.12.2 / 2026.1.1 or later
Fixed in 2025.12.22026.1.1
Interim mitigation

Upgrade to Discourse versions 2025.12.2, 2026.1.1, or 2026.2.0 to patch the vulnerability, or alternatively explicitly assign group permissions to each Data Explorer query or disable the plugin entirely.

Recommended fix High confidence

2025.12.2, 2026.1.1, or 2026.2.0 (any of these versions contain the fix)

  1. 1. Back up your Discourse instance before performing any upgrade
  2. 2. Access your Discourse server via SSH or admin console
  3. 3. Run the standard Discourse upgrade command: `cd /var/discourse && ./launcher rebuild app`
  4. 4. Alternatively, if using a hosted Discourse, apply the update through your admin panel
  5. 5. Verify the upgrade completed successfully by checking the Discourse version in /admin/dashboard
  6. 6. After upgrade, verify the Data Explorer plugin version matches the fixed release
  7. 7. Review existing Data Explorer queries to ensure appropriate group permissions are set as a security best practice
Caveat Standard Discourse minor version upgrades typically have minimal breaking changes; review release notes for any plugin compatibility notices

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

Fix this in Discourse Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2026-28218 in production — separate from our analysis above.

No notes yet

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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