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DiscourseApplication

CVE-2026-27481

MEDIUM · 5.3 CVSS v3.1 Published 2026-04-03
Fix available
A fix is available. Upgrade to after 2026.2.1 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges 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. From versions 2026.1.0-latest to before 2026.1.3, 2026.2.0-latest to before 2026.2.2, and 2026.3.0-latest to before 2026.3.0, an authorization bypass vulnerability allows unauthenticated or unauthorized users to view hidden (staff-only) tags and its associated data. All Discourse instances with tagging enabled and staff-only tag groups configured are impacted. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.

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

Discourse versions 2026.1.0 through 2026.2.1 and 2026.3.0-beta1 through 2026.3.0-beta2 contain an authorization bypass where tag visibility controls fail to properly restrict access to staff-only tags, allowing unauthenticated or unauthorized users to view hidden tags and their associated data.

MitigationUpgrade Discourse to version 2026.1.3, 2026.2.2, or 2026.3.0. If immediate upgrading is not possible, consider disabling tagging or removing staff-only tag group configurations as a temporary workaround.

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
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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. Check installed Discourse version
    Run `git -C /var/www/discourse rev-parse HEAD` or check the version displayed in the admin dashboard under /about. Compare the version number to the affected ranges: 2026.1.0-2026.1.2, 2026.2.0-2026.2.1, or 2026.3.0.
    Affected if The installed version matches one of the affected version ranges.
  2. Verify tagging is enabled
    In the Discourse admin panel, navigate to Settings > Tagging and check if 'enable tagging' is set to true. Alternatively, query the site settings table: `RAILS_ENV=production rails c` then `SiteSetting.tagging_enabled?`.
    Affected if Tagging is enabled (the vulnerability requires tagging to be active).
  3. Check for staff-only tag groups
    In the Discourse admin panel, navigate to Tags > Tag Groups and review each tag group for staff-only permissions. Alternatively, query the database: `SELECT name, permissions FROM tag_groups WHERE permissions LIKE '%staff%';`.
    Affected if One or more tag groups have staff-only permissions configured.

All three conditions must be true for the environment to be affected: the installed version is within the affected range, tagging is enabled, and at least one staff-only tag group exists.

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 a release after 2026.2.1
Interim mitigation

Upgrade Discourse to version 2026.1.3, 2026.2.2, or 2026.3.0. If immediate upgrading is not possible, consider disabling tagging or removing staff-only tag group configurations as a temporary workaround.

Recommended fix High confidence

Upgrade to Discourse 2026.1.3, 2026.2.2, or 2026.3.0 depending on your current branch

  1. 1. Backup your Discourse database and files before performing any upgrade.
  2. 2. Update Discourse to version 2026.1.3 (if currently on 2026.1.x), to version 2026.2.2 (if currently on 2026.2.x), or to version 2026.3.0 (if currently on 2026.3.0).
  3. 3. Follow the standard Discourse upgrade procedure for your deployment method (e.g., ./launcher rebuild app for Docker deployments).
  4. 4. Verify that staff-only tags are no longer accessible to unauthenticated or unauthorized users after the upgrade.

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-2026-27481 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