Security readout for executives and security teams
Plain-English summary
CVE-2021-20766 is a cross-site scripting issue in the Message function of Cybozu Garoon versions 4.0.0 through 5.0.2. An attacker could inject script content through unspecified vectors, potentially affecting users who view the crafted content. The public bundle does not provide CVSS scoring or detailed exploit conditions.
Executive priority
Treat this as a targeted product exposure check rather than a confirmed emergency. If affected Garoon versions are present, remediation should be scheduled promptly because XSS can affect user trust, session integrity, and internal communications.
Technical view
The record describes XSS in Cybozu Garoon Message, affecting versions 4.0.0 to 5.0.2. The injection vector is not specified in the supplied sources, and no CWE or CVSS data is included. Impact depends on user interaction, application exposure, and privileges associated with affected Garoon sessions.
Likely exposure
Organizations running Cybozu Garoon 4.0.0 to 5.0.2 are the identified exposure group, especially where the Message feature is accessible to untrusted or broad user populations.
Exploitation context
The source bundle does not show CISA KEV listing or cite active exploitation. It states only that a remote attacker may inject arbitrary script via unspecified vectors, so exploitation status and practical prerequisites remain unclear.
Researcher notes
Available evidence is sparse: no CVSS, CWE, detailed vector, or exploit status is provided in the bundle. Avoid assuming affected components beyond Cybozu Garoon Message 4.0.0 to 5.0.2. Use vendor and JVN advisories as the authoritative remediation sources.
Mitigation direction
- Identify all Cybozu Garoon deployments and their exact versions.
- Review Cybozu and JVN advisories for vendor-supported remediation guidance.
- Prioritize updating systems running Garoon 4.0.0 through 5.0.2.
- Restrict access to Garoon Message where exposure cannot be quickly remediated.
- Monitor vendor channels for any clarified fixed versions or workaround details.
Validation and detection
- Confirm whether any Garoon instance runs version 4.0.0 through 5.0.2.
- Verify whether the Message function is enabled and actively used.
- Check change records for vendor updates applied after August 18, 2021.
- Review application logs or reports for suspicious message content or unexpected script execution.
- Document findings against the Cybozu and JVN advisory references.
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-2021-20766 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.