CVE-2021-20829
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 due to the inadequate tag sanitization in GROWI versions v4.2.19 and earlier allows remote attackers to execute an arbitrary script on the web browser of the user who accesses a specially crafted page.
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 GROWI v4.2.19 and earlier due to inadequate tag sanitization allows remote attackers to inject arbitrary scripts into specially crafted pages that execute in the browsers of users who access them.
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<= 4.2.19CVSS 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 installed GROWI versionCheck the version number of your GROWI installation. This is typically visible in the admin panel under 'App Settings' or can be found in the package.json file if you have direct server access. On the server, you can also check using: grep -r 'version' /path/to/growi/package.json or check the GROWI about page in the web interface.Affected if The installed version is 4.2.19 or any version lower than 4.2.19.
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Confirm tag rendering is enabledGROWI is a wiki application that renders markdown and tags by default. Verify that the wiki functionality is active and users can create or edit pages with content that includes HTML-like tags or special characters. Check the 'Security Settings' in the admin panel for any tag or HTML-related configuration options.Affected if The wiki allows users to create or edit pages with custom content containing angle brackets or HTML-like tags, and no additional sanitization middleware is installed.
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Inspect content sanitization settingsIn the GROWI admin panel, navigate to 'Security Settings' and examine the 'XSS options' or 'Sanitization' configuration. Look for settings related to HTML tag filtering or content sanitization. Check if any custom sanitization rules are configured in the system.Affected if No XSS sanitization is enabled, or the built-in sanitization is present but uses an outdated configuration that does not properly handle the vulnerability present in versions 4.2.19 and earlier.
You are affected if your GROWI version is 4.2.19 or earlier and the wiki allows user-generated content with tags or special characters without additional external sanitization.
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 dataUpgrade GROWI to a version newer than v4.2.19 where proper tag sanitization has been implemented; validate the fix in a non-production environment before deploying to production.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20829 — 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-2021-20829 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
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