CVE-2021-20813
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 · uneditedCross-site scripting vulnerability in Edit screen of Content Data of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series) and Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series)) 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 confidenceCross-site scripting (XSS) vulnerability in the Edit screen of Content Data in Movable Type 7 r.4903 and earlier versions allows remote attackers to inject arbitrary JavaScript or HTML through unsanitized user input fields.
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>= 7.0, < 7.8.0CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify Movable Type versionAccess the Movable Type admin dashboard and navigate to System Overview or About section to view the installed version number, or check the version file in the Movable Type installation directory if you have filesystem accessAffected if The installed version is 7.0 through 7.7.x (any version >= 7.0 but < 7.8.0)
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Confirm Content Data feature is in useLog into the Movable Type admin panel and check if Content Data types have been created and are accessible through the Content Data menu option in the systemAffected if Content Data feature is enabled and content types are configured in the system
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Review Content Data edit permissionsCheck user roles and permissions to determine which user accounts have access to the Content Data edit screen in the admin interfaceAffected if Any user account with access to the Content Data edit screen exists in the system
You are affected if Movable Type 7 version is 7.0 through 7.7.x and Content Data feature with edit access is enabled in your environment.
Generated from the published advisory. Verify against your own configuration.
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 · scoped7.8.0
Apply available vendor patches for Movable Type 7 Series and Movable Type Advanced 7 Series. Until patched, implement output encoding and input validation on Content Data edit form fields.
Movable Type 7.8.0 or later
- 1. Back up your Movable Type installation including the database and all configuration files.
- 2. Review the Movable Type 7.8.0 release notes for any migration requirements or known issues.
- 3. Download Movable Type 7.8.0 or later from the official Movable Type website.
- 4. Test the upgrade in a staging environment before deploying to production.
- 5. Deploy the upgrade to production following standard deployment procedures.
- 6. Verify the installation is working correctly and the XSS vulnerability is resolved.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20813 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-20813 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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