CVE-2021-20801
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 · uneditedCybozu Remote Service 3.1.8 to 3.1.9 allows a remote authenticated attacker to conduct XML External Entity (XXE) attacks and obtain the information stored in the product via unspecified vectors. This issue occurs only when using Mozilla Firefox.
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 confidenceCybozu Remote Service versions 3.1.8 to 3.1.9 contains an XML External Entity (XXE) vulnerability that allows authenticated remote attackers to exploit improper XML parsing and obtain sensitive information stored in the product. The attack vector is limited to Mozilla Firefox users, suggesting a browser-specific parsing behavior or configuration issue.
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= 3.1.8= 3.1.9CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/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 Cybozu Remote Service versionAccess the product's system information or about page, or run the version command provided in the product documentationAffected if the installed version is 3.1.8 or 3.1.9
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Confirm version falls within affected rangeCompare your installed version against the affected range 3.1.8 to 3.1.9 inclusiveAffected if the version is exactly 3.1.8 or exactly 3.1.9
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Verify XML parsing is in useInspect whether the product processes XML data through user-supplied input, file uploads, or API calls that accept XML contentAffected if XML parsing functionality is enabled and accepts external input
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Check authentication statusVerify whether authentication is required for accessing the affected XML parsing featureAffected if the attacker can authenticate to the service (authentication is not disabled)
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Identify browser in useDetermine which web browser users employ to access the Cybozu Remote Service interfaceAffected if users access the service using Mozilla Firefox (the attack vector is limited to Firefox users)
You are affected if your Cybozu Remote Service is version 3.1.8 or 3.1.9, the XML parsing feature is enabled with external input, authentication can be obtained, and users access the service via Mozilla Firefox.
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 the vendor patch for CVE-2021-20801 or upgrade to a patched version. If no patch is available, disable external entity processing in the XML parser configuration and consider restricting Firefox usage until remediation is complete.
- Consultation6.0 h
- Implementation8.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20801 — 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-2021-20801 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
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data