DiscourseApplication

CVE-2023-43659

MEDIUM · 5.4 CVSS v3.1 Published 2023-10-16
Fix available
A fix is available. Upgrade to after 3.1.1 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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 platform for community discussion. Improper escaping of user input allowed for Cross-site Scripting attacks via the digest email preview UI. This issue only affects sites with CSP disabled. This issue has been patched in the 3.1.1 stable release as well as the 3.2.0.beta1 release. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled on the forum.

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

Cross-site scripting (XSS) vulnerability in Discourse's digest email preview UI due to improper escaping of user input. The vulnerability is exploitable when Content Security Policy (CSP) is disabled, allowing attackers to inject malicious scripts via the preview feature that execute in users' browsers.

MitigationUpgrade Discourse to version 3.1.1 (stable) or 3.2.0.beta1 or later, or enable Content Security Policy (CSP) headers on the forum as an alternative 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:<= 3.1.1= 3.2.0

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
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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
    Log into the Discourse admin panel and navigate to /about, or check the git version by running `git describe --tags` in the Discourse installation directory
    Affected if The version is 3.1.1 or earlier, or exactly 3.2.0
  2. Verify Content Security Policy status
    Access the Discourse admin panel, go to the Security settings, and check if Content Security Policy headers are enabled. Alternatively, inspect HTTP response headers for the presence of Content-Security-Policy headers when loading the forum
    Affected if CSP headers are disabled or not present in HTTP responses
  3. Confirm digest email preview accessibility
    Navigate to the digest email preview endpoint (typically /admin/email/digest-preview or similar path in the admin interface) to verify the feature is accessible
    Affected if The digest preview interface loads without errors and accepts user input in preview fields

You are affected if your installed Discourse version is 3.1.1 or earlier, or exactly 3.2.0, AND Content Security Policy headers are disabled in your environment.

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 3.1.1
Interim mitigation

Upgrade Discourse to version 3.1.1 (stable) or 3.2.0.beta1 or later, or enable Content Security Policy (CSP) headers on the forum as an alternative workaround.

Recommended fix High confidence

Discourse 3.1.1 stable (or 3.2.0.beta1 and above)

  1. Upgrade Discourse to version 3.1.1 stable or later (or 3.2.0.beta1 and above) to receive the security patch
  2. After upgrading, verify the digest email preview functionality works correctly
  3. Alternatively, if upgrade is not immediately possible, ensure Content Security Policy (CSP) is enabled on the Discourse forum to mitigate this vulnerability
  4. To enable CSP, go to Discourse admin settings and enable the 'content_security_policy' setting
Caveat Review Discourse release notes for 3.1.1 to check for any breaking changes specific to your setup

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
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

Scan for this in your stack

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dbcve dependency scanner

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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-2023-43659 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