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TYPO3CMS

CVE-2021-21340

MEDIUM · 5.4 CVSS v3.1 Published 2021-03-23
Fix available
A fix is available. Upgrade to 10.4.14 / 11.1.1 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
TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 10.4.14, 11.1.1 it has been discovered that database fields used as _descriptionColumn_ are vulnerable to cross-site scripting when their content gets previewed. A valid backend user account is needed to exploit this vulnerability. This is fixed in versions 10.4.14, 11.1.1 .

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

TYPO3 before versions 10.4.14 and 11.1.1 contains a stored cross-site scripting (XSS) vulnerability in the backend preview functionality. Database fields used as _descriptionColumn_ are not properly sanitized when their content is previewed, allowing a valid authenticated backend user to inject malicious scripts that execute when other backend users preview the affected content.

MitigationUpgrade to TYPO3 version 10.4.14, 11.1.1 or later. This is a patch-level upgrade that addresses the XSS vulnerability in the descriptionColumn preview 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
TYPO3CMS
Affected:>= 10.0.0, < 10.4.14>= 11.0.0, < 11.1.1

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. Determine the installed TYPO3 version
    Log into the TYPO3 backend and locate the version number in the About module (top-right menu > About) or check the composer.json file in the web root for the 'typo3/cms' version entry
    Affected if The installed version is less than 10.4.14 (for v10.x) or less than 11.1.1 (for v11.x)
  2. Identify if descriptionColumn is configured in custom tables
    Search the TCA configuration files (usually in EXT:*/Configuration/TCA/*.php) for occurrences of 'descriptionColumn' or '_descriptionColumn_' keys. These define which database fields are used as description columns in the backend preview
    Affected if Any custom TCA configuration defines a descriptionColumn that could be rendered in the backend preview
  3. Inspect the preview rendering code for descriptionColumn fields
    Examine the core file typo3/sysext/backend/Classes/Controller/PreviewController.php or equivalent, specifically how the descriptionColumn value is output in the preview. Look for whether the value is passed through htmlspecialchars or a sanitization function
    Affected if The preview rendering outputs descriptionColumn content without proper sanitization (no htmlspecialchars, strip_tags, or equivalent protection)
  4. Verify backend user access exists
    Check if there are active backend user accounts in the 'be_users' database table. The vulnerability requires a valid authenticated backend user to inject the payload
    Affected if Authenticated backend users exist and have access to content editing where descriptionColumn fields are used

You are affected if your TYPO3 installation version is below 10.4.14 or below 11.1.1 AND your system uses custom TCA configurations that define descriptionColumn fields that get rendered in the backend preview without sanitization.

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.

From vendor data
Upgrade available Upgrade to 10.4.14 / 11.1.1 or later
Fixed in 10.4.1411.1.1
Interim mitigation

Upgrade to TYPO3 version 10.4.14, 11.1.1 or later. This is a patch-level upgrade that addresses the XSS vulnerability in the descriptionColumn preview rendering.

Fix this in TYPO3 Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2021-21340 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