Security readout for executives and security teams
Plain-English summary
CVE-2021-20771 is a cross-site scripting issue in Cybozu Garoon E-Mail functions. A remote attacker could inject script into affected Garoon versions, potentially impacting users who view crafted content. The public bundle does not provide CVSS, exact vectors, or confirmed exploitation.
Executive priority
Treat this as a medium-priority remediation unless Garoon is internet-facing or heavily used for sensitive workflows. The main business risk is user session compromise or content manipulation through web scripting, but public evidence is incomplete.
Technical view
Cybozu Garoon 4.0.0 through 5.5.0 has XSS in some E-Mail functions. The source states arbitrary script injection via unspecified vectors. No CWE, CVSS, exploit details, or concrete fixed version is provided in the bundle.
Likely exposure
Organizations running Cybozu Garoon 4.0.0 through 5.5.0, especially where E-Mail functions are used. Internet-facing or broadly accessible Garoon instances should be prioritized. Exact vulnerable screens and prerequisites are not specified in the provided sources.
Exploitation context
The CVE is not listed in KEV, and the provided sources do not claim active exploitation. Because the vector is unspecified, assume exploitation requires interaction with affected E-Mail functionality until vendor guidance says otherwise.
Researcher notes
The useful public facts are limited to product range, XSS class, affected E-Mail functions, and unspecified vectors. Avoid assuming endpoint names, payload handling, authentication requirements, or patch versions without consulting the vendor advisory directly.
Mitigation direction
- Inventory all Cybozu Garoon deployments and record exact versions.
- Check Cybozu and JVN advisories for fixed versions or official workarounds.
- Upgrade affected Garoon instances according to vendor guidance.
- Limit access to Garoon E-Mail functions where exposure is unnecessary.
- Monitor for suspicious script-like content or unusual user session activity.
Validation and detection
- Confirm whether any Garoon instance runs versions 4.0.0 through 5.5.0.
- Verify whether E-Mail functionality is enabled and reachable by untrusted users.
- Confirm vendor-recommended updates or mitigations are applied.
- Review security monitoring for anomalous browser-side behavior in Garoon sessions.
- Document any remaining exposure where patching is delayed.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-20771 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://cs.cybozu.co.jp/2021/007206.htmlCVE reference · x_refsource_MISC
- https://jvn.jp/en/jp/JVN54794245/index.htmlCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.