CVE-2021-20771
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 some functions of E-Mail of Cybozu Garoon 4.0.0 to 5.5.0 allows a remote attacker to inject an arbitrary script 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 E-Mail function of Cybozu Garoon versions 4.0.0 through 5.5.0 allows remote attackers to inject arbitrary JavaScript or HTML through unspecified vectors within email handling. The medium severity (CVSS 6.1) indicates the attack requires user interaction or specific context but could lead to session hijacking, credential theft, or malicious actions performed in the user's context.
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>= 4.0.0, <= 5.5.0CVSS 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 if Cybozu Garoon is installedCheck your system for Cybozu Garoon installation by looking for the application in your program directories, or by accessing the web interface if it is a web application. Look for Garoon-specific directories, services, or login pages.Affected if Cybozu Garoon software is present in the environment
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Determine the installed Garoon versionAccess the Garoon administrator settings or system information page. Common paths include /g/ or /garoon/ on the web server. Look for version information typically found in 'System Settings' > 'System Information' or the login page footer.Affected if The installed version falls within the range 4.0.0 to 5.5.0 inclusive
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Confirm E-Mail function is accessibleLog into Garoon as a user (or admin) and navigate to the E-Mail or mail function module. Check if the email handling feature is enabled and accessible to users.Affected if The E-Mail function is enabled and users can create, view, or process emails within Garoon
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Inspect email-related input fields for output encodingCreate or view an email within Garoon and examine how user input is rendered. Test by entering special HTML characters (<, >, ", ') in email fields and check if they are rendered as plain text or executed as code when the email is viewed.Affected if User-supplied input in email fields is not properly encoded and can execute as JavaScript or display HTML
You are affected if Cybozu Garoon versions 4.0.0 through 5.5.0 are installed with the E-Mail function enabled and accessible to users.
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 dataApply vendor-supplied patches for Cybozu Garoon; if unavailable, implement robust input validation and output encoding on all email-related fields, and consider deploying Content Security Policy headers to mitigate XSS execution.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20771 — 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-2021-20771 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
- No spam, self-promotion, credentials, or personal data