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Ckeditor5Application · Ckeditor

CVE-2026-28343

MEDIUM · 6.1 CVSS v3.1 Published 2026-03-05
Fix available
A fix is available. Upgrade to 47.6.0 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
CKEditor 5 is a modern JavaScript rich-text editor with an MVC architecture. Starting in version 29.0.0 and prior to version 47.6.0, a cross-site scripting (XSS) vulnerability has been discovered in the General HTML Support feature. This vulnerability could be triggered by inserting specially crafted markup, leading to unauthorized JavaScript code execution, if the editor instance used an unsafe General HTML Support configuration. This issue has been patched in version 47.6.0.

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

Cross-site scripting (XSS) vulnerability in CKEditor 5's General HTML Support feature (versions 29.0.0 through 47.6.0) allows remote attackers to execute arbitrary JavaScript code by inserting specially crafted HTML markup when the editor uses an unsafe General HTML Support configuration.

MitigationUpgrade CKEditor 5 to version 47.6.0 or later. Review and harden General HTML Support configurations to prevent unsafe markup processing, and validate existing deployments for potential exploitation.

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
Ckeditor5Application
Affected:< 47.6.0

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 CKEditor 5 installation and version
    Locate the CKEditor 5 package in your project (typically in package.json, node_modules/@ckeditor/ckeditor5, or the editor bundle). Run 'npm list @ckeditor/ckeditor5' or inspect the package.json to find the installed version number.
    Affected if The installed version is between 29.0.0 and 47.6.0 (exclusive of 47.6.0)
  2. Confirm General HTML Support feature is enabled
    Search your editor initialization code for references to 'GeneralHtmlSupport' or 'generalHtmlSupport' in the plugins configuration array. Check if this feature is imported and added to the editor's plugin list.
    Affected if General HTML Support is present in the active plugin configuration
  3. Inspect General HTML Support configuration for unsafe markup
    Locate the General HTMLSupport configuration object in your editor setup. Review the allowed tags and attributes settings. Look for permissive configurations that allow HTML elements without strict sanitization, particularly script tags, event handler attributes (onclick, onerror, etc.), or wildcard allowlists.
    Affected if The configuration permits raw script tags, JavaScript event handlers, or other markup capable of executing arbitrary scripts

You are affected if CKEditor 5 version is 29.0.0 through 47.6.0 AND the General HTML Support feature is enabled with an unsafe configuration that allows script execution via HTML markup.

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 47.6.0 or later
Fixed in 47.6.0
Interim mitigation

Upgrade CKEditor 5 to version 47.6.0 or later. Review and harden General HTML Support configurations to prevent unsafe markup processing, and validate existing deployments for potential exploitation.

Recommended fix High confidence

47.6.0

  1. Identify the package.json or dependency file that specifies ckeditor5 version
  2. Update the ckeditor5 dependency to version 47.6.0 or higher (e.g., "ckeditor5": "^47.6.0")
  3. Run the package manager install command (npm install, yarn install, or pnpm install) to fetch the updated version
  4. Verify the installed version matches 47.6.0 or later using npm list ckeditor5 or equivalent
  5. Test the CKEditor 5 instance to ensure the General HTML Support feature functions correctly after the upgrade
Caveat Check CKEditor 5 release notes between your current version and 47.6.0 for any breaking changes or migration requirements

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

Fix this in Ckeditor5 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
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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-2026-28343 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