dbcve.org
Remote Service ManagerApplication · Cybozu

CVE-2021-20797

MEDIUM · 5.4 CVSS v3.1 Published 2021-10-13
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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
Cross-site script inclusion vulnerability in the management screen of Cybozu Remote Service 3.1.8 allows a remote authenticated attacker to obtain the information stored in the product. 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 confidence

Cross-site script inclusion (XSSI) vulnerability in the management screen of Cybozu Remote Service 3.1.8 allows an authenticated attacker to steal sensitive data by tricking logged-in users into visiting a malicious page. This XSSI flaw enables the attacker to include the vulnerable application's JSON/JS responses in an external site, exfiltrating authenticated user data. The Firefox-specific nature suggests exploitation relies on particular browser behavior for reading response data.

MitigationImplement anti-CSRF tokens for sensitive endpoints, use JSON with JavaScript wrapper techniques, and configure SameSite cookie attributes to prevent cross-site inclusion of sensitive responses.

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
Remote Service ManagerApplication
Affected:= 3.1.8

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
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/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 Cybozu Remote Service Manager installation
    Locate the application in your system inventory or check installed programs list for 'Cybozu Remote Service Manager' or 'Cybozu Remote Service'
    Affected if The product Cybozu Remote Service Manager is not present in your environment
  2. Determine installed version number
    Check the application's version information - typically found in the program properties, about dialog, or version file within the installation directory
    Affected if The installed version is exactly 3.1.8 (note: only this specific version is affected)
  3. Verify management interface accessibility
    Confirm the web management interface is accessible by accessing the admin/management URL for Cybozu Remote Service
    Affected if The management screen is publicly or untrusted network accessible without additional authentication barriers
  4. Check for anti-CSRF token implementation
    Inspect the management screen's AJAX responses and form submissions to see if CSRF tokens are present in requests
    Affected if Sensitive endpoints lack anti-CSRF token validation (this is the vulnerable condition)
  5. Review cookie SameSite attributes
    Examine browser developer tools or server configuration for SameSite cookie attributes on management session cookies
    Affected if Cookies are set without SameSite=Strict or SameSite=Lax attributes

Your environment is affected only if Cybozu Remote Service Manager version 3.1.8 is installed AND the management interface is accessible AND security measures like anti-CSRF tokens and SameSite cookies are not implemented on sensitive endpoints.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement anti-CSRF tokens for sensitive endpoints, use JSON with JavaScript wrapper techniques, and configure SameSite cookie attributes to prevent cross-site inclusion of sensitive responses.

Recommended fix Moderate confidence

Contact Cybozu support for the specific fixed release (check kb.cybozu.support for version 3.1.9 or later)

  1. Check the current version of Cybozu Remote Service Manager in use - confirm it is version 3.1.8
  2. Contact Cybozu customer support or check kb.cybozu.support for the latest patched version of Remote Service Manager
  3. Upgrade to the fixed version as specified in the official Cybozu security advisory
  4. After upgrading, verify that the management screen is functioning correctly
  5. Test the fix using Mozilla Firefox to confirm the XSS vulnerability is resolved
Caveat Review Cybozu release notes for any changes in functionality between 3.1.8 and the fixed version before upgrading

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

Fix this in Remote Service Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2021-20797 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