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DiscourseApplication

CVE-2025-48062

MEDIUM · 6.1 CVSS v3.1 Published 2025-06-09
Fix available
A fix is available. Upgrade to 3.4.4 / 3.5.0 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch, certain invites via email may result in HTML injection in the email body if the topic title includes HTML. This includes inviting someone (without an account) to a PM and inviting someone (without an account) to a topic with a custom message. This issue is patched in version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch. This can be worked around if the relevant templates are overridden without `{topic_title}`.

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

This is a stored HTML injection vulnerability in Discourse's email invite system. When inviting users without accounts to private messages or topics with custom messages, the topic title is included in email templates without proper HTML sanitization. If an attacker creates a topic with an HTML payload in the title and then sends an invite, the HTML will be rendered in the invite email.

MitigationUpgrade Discourse to version 3.4.4 (stable), 3.5.0.beta5 (beta), or 3.5.0.beta6-dev (tests-passed). Alternatively, override the relevant email templates to remove the {topic_title} variable or sanitize it before rendering.

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:< 3.4.4< 3.5.0= 3.5.0

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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/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. Check your Discourse version
    Access the Discourse admin panel and navigate to /admin/about or use the discourse version command in the CLI. Compare the installed version against the affected ranges: < 3.4.4, < 3.5.0, or = 3.5.0
    Affected if The installed version falls within the affected ranges (< 3.4.4, < 3.5.0, or = 3.5.0)
  2. Identify if the email invite feature is in use
    Check your admin panel for sent invites, particularly invites sent to non-existing users with custom messages. Look for invite records in the database table that have a custom_message value set
    Affected if Invites with custom_message have been sent to users without accounts on private messages or topics
  3. Inspect topic titles for HTML content
    Query the database topics table for titles containing HTML tags. Look for topics where the title column contains strings like <script>, <iframe>, or other HTML markup that was not intentionally created by administrators
    Affected if Any topic titles contain unescaped HTML tags that could execute in an email context
  4. Review email template files
    Examine the email templates used for invites, specifically those that include the {topic_title} variable. Check if templates are using raw title insertion without HTML sanitization
    Affected if Email templates include {topic_title} without proper sanitization

You are affected if your Discourse version is less than 3.4.4, less than 3.5.0, or exactly 3.5.0 AND you have used the email invite feature with custom messages to users without accounts.

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 3.4.4 / 3.5.0 or later
Fixed in 3.4.43.5.0
Interim mitigation

Upgrade Discourse to version 3.4.4 (stable), 3.5.0.beta5 (beta), or 3.5.0.beta6-dev (tests-passed). Alternatively, override the relevant email templates to remove the {topic_title} variable or sanitize it before rendering.

Recommended fix High confidence

Discourse 3.4.4 (stable) / 3.5.0.beta5 (beta) / 3.5.0.beta6-dev (tests-passed)

  1. Identify which Discourse branch you are currently running (stable, beta, or tests-passed)
  2. For stable branch users: upgrade to version 3.4.4 or later
  3. For beta branch users: upgrade to version 3.5.0.beta5 or later
  4. For tests-passed branch users: upgrade to version 3.5.0.beta6-dev or later
  5. After upgrade, verify the email invite functionality works correctly with HTML-containing topic titles

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
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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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-2025-48062 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