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Movable TypeApplication · Sixapart

CVE-2021-20814

MEDIUM · 6.1 CVSS v3.1 Published 2021-08-26
Fix available
A fix is available. Upgrade to 7.8.0 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
Cross-site scripting vulnerability in Setting screen of ContentType Information Widget Plugin of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series), Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series), and Movable Type Premium 1.44 and earlier) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.

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

Cross-site scripting (XSS) vulnerability in the Setting screen of the ContentType Information Widget Plugin in Movable Type versions 7 r.4903 and earlier, Movable Type Advanced 7 r.4903 and earlier, and Movable Type Premium 1.44 and earlier. The vulnerability allows remote attackers to inject arbitrary JavaScript or HTML through unspecified vectors in the widget settings.

MitigationUpdate Movable Type to versions beyond r.4903 (MT7) and 1.44 (Premium) when patches are released. Alternatively, implement input validation and output encoding on the ContentType Information Widget's Setting screen to neutralize malicious script injection.

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
Movable TypeApplication
Affected:<= 1.44>= 7.0, < 7.8.0

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. Identify Movable Type installation and version
    Locate the Movable Type installation directory and check the version file or admin interface for the installed Movable Type version (MT7 or Premium)
    Affected if The installed version is 7.0 through r.4903 (inclusive) for MT7, or 1.44 or earlier for Movable Type Premium
  2. Confirm ContentType Information Widget is present
    Check if the ContentType Information Widget plugin is installed by examining the plugins directory or the widget list in the Movable Type admin interface
    Affected if The ContentType Information Widget plugin is found in the installation
  3. Verify widget settings are accessible
    Access the Setting screen for the ContentType Information Widget through the Movable Type admin interface (typically via Widgets or Plugin settings)
    Affected if The widget settings screen is accessible and allows configuration of the ContentType Information Widget

A user is affected if they run Movable Type 7 r.4903 or earlier (or Premium 1.44 or earlier) AND have the ContentType Information Widget enabled with accessible settings, allowing potential XSS injection through the widget configuration.

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 7.8.0 or later
Fixed in 7.8.0
Interim mitigation

Update Movable Type to versions beyond r.4903 (MT7) and 1.44 (Premium) when patches are released. Alternatively, implement input validation and output encoding on the ContentType Information Widget's Setting screen to neutralize malicious script injection.

Recommended fix Moderate confidence

Movable Type 7.8.0 (or later within the 7.x series)

  1. 1. Back up your Movable Type installation, including the database and all configuration files.
  2. 2. Review the Movable Type 7.8.0 release notes for any specific upgrade requirements or migration steps.
  3. 3. Download Movable Type 7.8.0 or later from the official Movable Type website (movabletype.org).
  4. 4. Before applying the upgrade, test the upgrade in a staging environment to ensure compatibility with your existing plugins and templates.
  5. 5. Install the upgrade following the standard Movable Type upgrade procedure: upload the new files, run any database migrations if prompted, and verify the installation.
  6. 6. After upgrading, verify that the ContentType Information Widget Plugin is functioning correctly and that the XSS vulnerability is resolved.
  7. 7. Test the application thoroughly, especially the Setting screen of ContentType Information Widget Plugin, to confirm the fix.
Caveat Review release notes for potential template or plugin compatibility changes when upgrading from older 7.x versions

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

Fix this in Movable Type Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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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-2021-20814 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