FedoraOperating system · Fedoraproject
CVE-2020-9440
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 · uneditedA cross-site scripting (XSS) vulnerability in the WSC plugin through 5.5.7.5 for CKEditor 4 allows remote attackers to run arbitrary web script inside an IFRAME element by injecting a crafted HTML element into the editor.
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 confidenceA stored cross-site scripting (XSS) vulnerability exists in the WebSpellChecker (WSC) plugin for CKEditor 4 (versions through 5.5.7.5). Attackers can inject crafted HTML elements into the editor that execute arbitrary JavaScript within an IFRAME context, potentially compromising other users viewing the injected content.
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
FedoraOperating system
= 30= 31= 32= 4.0<= 5.5.7.5CVSS 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 CKEditor 4 installationSearch for ckeditor.js or CKEditor-related JavaScript files in your web application directories, or check your JavaScript dependencies for CKEditor 4 presence.Affected if CKEditor 4 is present in your environment
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Locate the WebSpellChecker pluginLook for the 'wsc' or 'webspellchecker' directory within your CKEditor plugins folder, or check for 'wsc' in the CKEditor plugins configuration.Affected if The WSC plugin directory or references exist in your CKEditor installation
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Determine WSC plugin versionOpen the plugin configuration file (typically within the wsc folder, often named config.js or version info) and locate the version number, or check your package.json/npm dependencies for the webspellchecker version.Affected if The WSC plugin version is 5.5.7.5 or lower, or no version can be determined (treat as vulnerable)
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Verify spell-check feature is enabledCheck your CKEditor configuration (config.js, initialization code, or CMS settings) for the presence of 'wsc' or 'webspellchecker' in the extraPlugins or plugins list, or confirm spell-checking is actively used in the editor.Affected if The WSC plugin is loaded and enabled in your CKEditor configuration
You are affected if CKEditor 4 with the WSC plugin version 5.5.7.5 or lower is installed and the spell-check functionality 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.
From vendor dataUpdate the WSC plugin to a version newer than 5.5.7.5, or disable the plugin if spell-checking functionality is not required. Implement output encoding when rendering editor content to prevent script execution.
Fix this in Fedora
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-9440 — 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-2020-9440 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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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.
- 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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