dbcve.org
DiscourseApplication

CVE-2026-27021

MEDIUM · 5.3 CVSS v3.1 Published 2026-02-26
Fix available
A fix is available. Upgrade to 2025.12.0 / 2026.1.1 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. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, the voters endpoint in the poll plugin lacked post visibility checks which allowed unauthorized access to voters details of polls in any post. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

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

The poll plugin in Discourse contains an information disclosure vulnerability where the voters endpoint does not perform post visibility checks before returning voter details. This allows any authenticated or unauthenticated user to retrieve the list of voters for polls in posts they should not have access to, exposing voting behavior on private or restricted content.

MitigationUpgrade Discourse to version 2025.12.2, 2026.1.1, or 2026.2.0 which contains the patch. No workaround is available.

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:< 2025.12.0>= 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
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 Discourse version
    Access the Discourse admin panel or check the version file in the Discourse installation directory. Typically found via /admin/about or by running `git log` in the Discourse repository.
    Affected if The installed version is < 2025.12.0, or >= 2026.1.0 and < 2026.1.1, or exactly 2026.2.0
  2. Verify poll plugin is enabled
    Navigate to the Discourse admin panel and check the installed plugins list. The poll plugin is typically bundled but must be enabled in site settings.
    Affected if The poll plugin is enabled in the Discourse installation
  3. Identify polls in restricted posts
    Review posts that have poll functionality enabled and are set to private, restricted, or visible only to certain groups. Check if polls exist in categories or topics with limited access controls.
    Affected if Polls exist in posts or topics that have visibility restrictions (private categories, group-restricted topics, or TL0/TL1 user-only content)
  4. Check voter endpoint accessibility
    Attempt to access the voters endpoint for a poll in a restricted post without proper authentication or group membership. The endpoint typically follows the pattern /polls/voters or similar.
    Affected if Voter information is returned for polls in restricted posts without requiring post visibility verification

You are affected if your Discourse version is in the affected range AND the poll plugin is enabled AND you have polls in posts with visibility restrictions that could expose voter data through the unprotected endpoint.

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 2025.12.0 / 2026.1.1 or later
Fixed in 2025.12.02026.1.1
Interim mitigation

Upgrade Discourse to version 2025.12.2, 2026.1.1, or 2026.2.0 which contains the patch. No workaround is available.

Recommended fix High confidence

2025.12.2 (for 2025.x branch), 2026.1.1 (for 2026.1.x branch), or 2026.2.0 (for 2026.2.x branch)

  1. 1. Identify the current Discourse version by checking the admin dashboard or running `git log` in the Discourse directory
  2. 2. Determine which version branch you are on (2025.x, 2026.1.x, or 2026.2.x)
  3. 3. For 2025.x branch users: upgrade to version 2025.12.2 or later
  4. 4. For 2026.1.x branch users: upgrade to version 2026.1.1 or later
  5. 5. For 2026.2.x branch users: upgrade to version 2026.2.0 or later
  6. 6. Pull the latest Discourse code using `./launcher stop app && git pull && ./launcher start app`
  7. 7. Run database migrations if required: `cd /var/discourse && ./launcher rebuild app`
  8. 8. Verify the upgrade completed successfully by checking the Discourse admin panel version display
Caveat Standard Discourse minor version upgrades typically do not include breaking changes, but review release notes before upgrading

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

Fix this in Discourse Scoped from the published advisory
  • Consultation3.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,950
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,120.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-27021 — 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-2026-27021 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