Security readout for executives and security teams
Plain-English summary
CVE-2021-20764 affects Cybozu Garoon attachment handling in versions 4.0.0 through 5.0.2. The public description says improper input validation may let a remote attacker alter attachment data. The source bundle does not provide CVSS, detailed prerequisites, or confirmed exploit activity.
Executive priority
Treat this as an integrity risk for organizations using affected Garoon versions. Prioritize inventory and vendor-guided remediation, but avoid assuming active exploitation or critical severity from the current evidence.
Technical view
The issue is an improper input validation flaw in the Attaching Files feature of Cybozu Garoon. A remote attacker may alter data associated with attachments. Available sources identify the affected version range as 4.0.0 to 5.0.2, but do not provide CWE, CVSS metrics, authentication requirements, or technical exploit details.
Likely exposure
Exposure is limited to organizations running Cybozu Garoon versions 4.0.0 through 5.0.2, especially where Garoon is reachable by remote users. The bundle does not identify affected CPEs or deployment conditions.
Exploitation context
The CVE is not listed as KEV in the provided bundle, and no cited source here confirms active exploitation. The available evidence only supports a remote data-alteration risk in attachment handling.
Researcher notes
Evidence is thin: no CVSS, CWE, exploit prerequisites, or patch details are included in the provided bundle. Analysis should stay anchored to the affected range and attachment data alteration impact unless the Cybozu or JVN advisories provide more detail.
Mitigation direction
- Identify all Cybozu Garoon deployments and their exact versions.
- Review Cybozu and JVN guidance for fixed versions or vendor mitigations.
- Prioritize leaving versions 4.0.0 through 5.0.2 if vendor guidance confirms an update path.
- Limit remote access to Garoon where business operations allow.
- Monitor attachment changes for unexpected modification until remediation is complete.
Validation and detection
- Confirm whether any Garoon instance runs version 4.0.0 through 5.0.2.
- Check whether the Attaching Files feature is used for sensitive workflows.
- Review attachment audit trails for unusual modifications.
- Verify remediation against Cybozu or JVN advisory criteria.
- Document any compensating access controls applied before patching.
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-2021-20764 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.