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DiscourseApplication

CVE-2026-44786

HIGH · 7.5 CVSS v3.1 Published 2026-06-12
Fix available
A fix is available. Upgrade to 2026.1.0 / 2026.1.4 or later.
See remediation →
84/100
Remediation priority · High
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 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, chat events for public category channels are published to MessageBus without permission scoping, so any MessageBus subscriber without chat enabled could receive chat message payloads in real time. 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 confidence

In affected Discourse versions, chat events for public category channels are published to MessageBus without permission scoping. This allows any MessageBus subscriber—even those without chat enabled—to receive chat message payloads in real time, resulting in unauthorized information disclosure of chat content.

MitigationUpgrade Discourse to version 2026.1.4, 2026.3.1, 2026.4.1, or 2026.5.0-latest.1 or later to apply the patch that implements proper permission scoping on MessageBus publications.

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>= 2026.1.0, < 2026.1.4>= 2026.3.0, < 2026.3.1>= 2026.4.0, < 2026.4.1= 2026.5.0

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
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/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
    Run `git -C /var/www/discourse describe --tags` or check the version file at /var/www/discourse/VERSION, or look at the Discourse admin dashboard under /about for the current version number
    Affected if The installed version matches any of the affected ranges: < 2026.1.0, 2026.1.0 to 2026.1.3, 2026.3.0, 2026.4.0, or 2026.5.0 exactly
  2. Verify Chat plugin is enabled
    Check the Discourse admin panel at /admin/plugins or inspect the database table `plugins` where name like '%chat%', or check if the chat component appears in the site's plugin list
    Affected if Chat is enabled and the Discourse version is in the affected list
  3. Confirm MessageBus is in use
    Check if MessageBus is running: look for messagebus process via `ps aux | grep messagebus` or check that MessageBus is configured in /var/www/discourse/config/initializers/message_bus.rb
    Affected if MessageBus is active and the version is vulnerable
  4. Check for public category channels with chat
    Query the database: `SELECT id, name FROM categories WHERE chat_enabled = true AND read_restricted = false;` or inspect the Discourse admin panel under Chat > Settings for public channels
    Affected if There exist public (non-restricted) category channels with chat enabled on a vulnerable version

If the installed Discourse version is in the affected list, Chat is enabled, and public category channels exist with chat, the environment is vulnerable to unauthorized chat message disclosure via MessageBus.

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 2026.1.0 / 2026.1.4 / 2026.3.1 or later
Fixed in 2026.1.02026.1.42026.3.1
Interim mitigation

Upgrade Discourse to version 2026.1.4, 2026.3.1, 2026.4.1, or 2026.5.0-latest.1 or later to apply the patch that implements proper permission scoping on MessageBus publications.

Recommended fix High confidence

2026.1.4, 2026.3.1, 2026.4.1, or 2026.5.0 (whichever is appropriate for your branch)

  1. 1. Identify the currently installed Discourse version by checking the /admin dashboard or running `git log -1` in the Discourse directory
  2. 2. If running version >= 2026.1.0 and < 2026.1.4, plan upgrade to version 2026.1.4 or later
  3. 3. If running version >= 2026.3.0 and < 2026.3.1, plan upgrade to version 2026.3.1 or later
  4. 4. If running version >= 2026.4.0 and < 2026.4.1, plan upgrade to version 2026.4.1 or later
  5. 5. For any version < 2026.1.0, plan upgrade to 2026.5.0 or later to get all patches
  6. 6. Before upgrading in production, test the upgrade in a staging environment to verify compatibility
  7. 7. Perform the upgrade following standard Discourse upgrade procedures (typically `git pull` and `./launcher rebuild app`)
  8. 8. After upgrade, verify the MessageBus configuration includes proper permission scoping for chat events
Caveat Standard Discourse upgrade considerations apply - review release notes for any breaking changes between your current version and target version

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
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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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-2026-44786 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