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DiscourseApplication

CVE-2023-40588

MEDIUM · 6.5 CVSS v3.1 Published 2023-09-15
Fix available
A fix is available. Upgrade to 3.1.1 or later.
See remediation →
71/100
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 version 3.1.1 of the `stable` branch and version 3.2.0.beta1 of the `beta` and `tests-passed` branches, a malicious user could add a 2FA or security key with a carefully crafted name to their account and cause a denial of service for other users. The issue is patched in version 3.1.1 of the `stable` branch and version 3.2.0.beta1 of the `beta` and `tests-passed` branches. There are no known workarounds.

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 Discourse prior to versions 3.1.1 (stable) and 3.2.0.beta1 (beta/tests-passed), a user can add a 2FA or security key with a specially crafted name that triggers a denial of service condition affecting other users of the platform. The vulnerability lies in insufficient input validation or sanitization of the security key name field, which can be exploited to cause resource exhaustion or application failure for other users.

MitigationUpgrade Discourse to version 3.1.1 (stable branch) or 3.2.0.beta1 (beta/tests-passed branches). No workarounds are available, so immediate patching is required.

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:< 3.1.1= 1.1.0= 1.2.0= 1.3.0= 1.4.0= 1.5.0= 1.6.0= 1.7.0= 1.8.0= 1.9.0= 2.0.0= 2.1.0

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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
    Log into the Discourse admin panel and navigate to /admin/about, or check the version file in the Discourse installation directory (typically in the /var/discourse directory or via git tag). Compare the version to the affected ranges: stable versions below 3.1.1, beta versions below 3.2.0.beta1, or versions 1.1.0 through 1.9.0.
    Affected if The installed version is below 3.1.1 (stable) or below 3.2.0.beta1 (beta), or matches any of 1.1.0 through 1.9.0.
  2. Verify 2FA is enabled
    In the Discourse admin panel, navigate to Settings > User Preferences > enable_2fa. Alternatively, query the site settings database table for the enable_2fa setting.
    Affected if 2FA is enabled on the instance.
  3. Check security key feature status
    In the Discourse admin panel, navigate to Settings > Login > allow_2fa_and_webauthn. Alternatively, query the site settings for allow_2fa_and_webauthn setting value.
    Affected if The security key / 2FA feature is available or enabled.
  4. Review recent 2FA/security key additions
    Query the user_second_factors database table for any security keys with unusually long name fields, or check admin audit logs for patterns of security key creation with names exceeding typical lengths.
    Affected if There are user security keys with excessively long or crafted names present in the database.

The environment is affected if Discourse version is below 3.1.1 (stable) or below 3.2.0.beta1 (beta), and the 2FA or security key feature is enabled, allowing users to add security keys that could trigger denial of service.

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 3.1.1 or later
Fixed in 3.1.1
Interim mitigation

Upgrade Discourse to version 3.1.1 (stable branch) or 3.2.0.beta1 (beta/tests-passed branches). No workarounds are available, so immediate patching is required.

Recommended fix High confidence

Discourse 3.1.1 (stable branch) or 3.2.0.beta1 (beta/tests-passed branches)

  1. 1. Back up your Discourse instance (database, uploads, and configuration files) before proceeding with any upgrade
  2. 2. If using the official Docker install method, navigate to your Discourse container directory and run `./launcher rebuild app` to fetch and apply the updated version
  3. 3. If using a different installation method, follow your distribution-specific upgrade instructions using the official Discourse repository
  4. 4. After upgrade completes, verify that the site is accessible and the 2FA/security key functionality works correctly
  5. 5. Test that the resource exhaustion issue is resolved by attempting to add a 2FA device with a long name (the operation should now be properly limited)
Caveat Standard Discourse upgrades may require reviewing plugin and theme compatibility; test in staging first

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
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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Scan for this in your stack

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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-2023-40588 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