CVE-2026-47264
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 · uneditedDiscourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, DetailedTagSerializer#tag_group_names returned every tag group a tag belonged to without filtering against the requesting user's visibility. With SiteSetting.tags_listed_by_group enabled, anonymous and unprivileged users hitting TagsController#info (which is exempt from requires_login) could read the names of tag groups restricted to specific user groups or non-visible categories. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.
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 confidenceDiscourse's DetailedTagSerializer#tag_group_names method failed to filter tag groups based on user visibility permissions. With SiteSetting.tags_listed_by_group enabled, the unauthenticated TagsController#info endpoint exposed names of tag groups restricted to specific user groups or non-visible categories, allowing anonymous users to enumerate sensitive internal tagging structure.
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< 2026.1.0>= 2026.1.0, < 2026.1.4>= 2026.3.0, < 2026.3.1>= 2026.4.0, < 2026.4.1= 2026.5.0CVSS 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 checksWork through these to decide whether this CVE applies to you.
-
Identify Discourse installation and versionLocate your Discourse installation and determine the installed version by checking the version file, admin dashboard, or running `Discourse::VERSION` in the Rails console. Compare against affected ranges: < 2026.1.0, >= 2026.1.0 and < 2026.1.4, >= 2026.3.0 and < 2026.3.1, >= 2026.4.0 and < 2026.4.1, or = 2026.5.0Affected if The installed version falls within any of the affected version ranges
-
Verify tags_listed_by_group SiteSetting is enabledAccess the Discourse admin panel, navigate to Settings > Tags, and check whether the 'tags_listed_by_group' setting is turned ON. Alternatively, query the SiteSetting via Rails console: `SiteSetting.tags_listed_by_group`Affected if tags_listed_by_group is enabled (set to true)
-
Confirm existence of restricted tag groupsIn the Discourse admin panel, go to Tags > Tag Groups and review which tag groups exist. Check which groups have permissions restricted to specific user groups or are assigned to non-visible categoriesAffected if There are tag groups configured with restricted group permissions or assigned to private categories
-
Test anonymous access to TagsController#info endpointWithout logging in (as an anonymous user), send a GET request to the /tags/info endpoint (for example, /tags or /tag/info/:tag_name) and examine the response to see if it includes tag group names that should be restrictedAffected if The endpoint returns tag group names that are restricted to authenticated users or specific groups
You are affected if your Discourse version is in the affected list AND tags_listed_by_group is enabled AND you have restricted tag groups AND the tags/info endpoint is accessible to anonymous users.
Generated from the published advisory. Verify against your own configuration.
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 · scoped2026.1.02026.1.42026.3.1
Upgrade Discourse to version 2026.1.4, 2026.3.1, 2026.4.1, or 2026.5.0-latest.1. As a temporary mitigation, disable the tags_listed_by_group SiteSetting if operationally feasible.
2026.5.0-latest.1 (or 2026.4.1, 2026.3.1, 2026.1.4 as fallback options)
- Identify your current Discourse version by checking the admin panel or running `cd /var/discourse && git rev-parse HEAD`
- Backup your Discourse instance including database and uploaded files before proceeding
- Run the Discourse upgrade command: `cd /var/discourse && ./launcher rebuild app`
- Alternatively, if using a managed hosting solution, use their provided upgrade mechanism
- After upgrade, verify the patch is applied by checking the version in admin panel matches 2026.1.4, 2026.3.1, 2026.4.1, or 2026.5.0-latest.1
- Test that TagsController#info endpoint no longer exposes restricted tag group names to anonymous users
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-47264 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-47264 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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.
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.
- 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