dbcve.org
DiscourseApplication

CVE-2025-23023

HIGH · 8.2 CVSS v3.1 Published 2025-02-04
Fix available
A fix is available. Upgrade to 3.3.2 or later.
See remediation →
91/100
Remediation priority · Urgent
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 platform for community discussion. In affected versions an attacker can carefully craft a request with the right request headers to poison the anonymous cache (for example, the cache may have a response with missing preloaded data). This issue only affects anonymous visitors of the site. This problem has been patched in the latest version of Discourse. Users are advised to upgrade. Users unable to upgrade may disable anonymous cache by setting the `DISCOURSE_DISABLE_ANON_CACHE` environment variable to a non-empty value.

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 · moderate confidence

This is a cache poisoning vulnerability in Discourse where attackers can manipulate request headers to poison the anonymous user cache, resulting in responses with missing preloaded data. Only anonymous visitors are affected.

MitigationUpgrade to the latest patched version of Discourse, or temporarily disable anonymous caching by setting the DISCOURSE_DISABLE_ANON_CACHE environment variable to a non-empty value as a 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:< 3.3.2

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
None
Integrity
High
Availability
Low

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

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 and navigate to /admin/about, or run `git log -1 --format='%H %s'` in the Discourse directory, or check the version file in the container/image metadata
    Affected if The installed version is below 3.3.2
  2. Verify anonymous caching is enabled
    Check the Discourse environment variables for DISCOURSE_DISABLE_ANON_CACHE - if this variable is unset or set to an empty value, anonymous caching is enabled. Run `echo $DISCOURSE_DISABLE_ANON_CACHE` or inspect the app.yml environment section
    Affected if DISCOURSE_DISABLE_ANON_CACHE is not set or is empty, meaning anonymous caching is active
  3. Confirm anonymous access is allowed
    Check the Discourse site settings at /admin/site_settings or inspect the trust_level setting and ensure the site allows unauthenticated (anonymous) visitors
    Affected if Anonymous access is permitted and unauthenticated users can browse the site
  4. Check for cache-related headers in responses
    Make an unauthenticated request to the Discourse site and inspect the response headers for cache-related headers such as X-Cache or similar caching headers. Also check if preloaded data appears in the HTML response
    Affected if The response contains caching headers indicating the anonymous user cache is in use, and preloaded data may be missing from responses to anonymous users

You are affected if running Discourse version below 3.3.2 with anonymous caching enabled and anonymous users can access the site, as the cache poisoning vulnerability can be exploited to cause missing preloaded data.

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 3.3.2 or later
Fixed in 3.3.2
Interim mitigation

Upgrade to the latest patched version of Discourse, or temporarily disable anonymous caching by setting the DISCOURSE_DISABLE_ANON_CACHE environment variable to a non-empty value as a workaround.

Recommended fix High confidence

Discourse 3.3.2 or later

  1. Upgrade Discourse to version 3.3.2 or later (the latest stable release)
  2. Verify the upgrade completes successfully and the application is functioning normally
  3. As a temporary mitigation if immediate upgrade is not possible, set the environment variable DISCOURSE_DISABLE_ANON_CACHE to a non-empty value to disable the anonymous cache

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

Fix this in Discourse Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

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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-2025-23023 in production — separate from our analysis above.

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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