Security readout for executives and security teams
Plain-English summary
CVE-2021-20765 is a cross-site scripting issue in Cybozu Garoon's Bulletin feature. A remote attacker could inject script content through unspecified vectors, potentially affecting users who view malicious bulletin content. The public data does not provide a CVSS score, specific attack path, or confirmed exploitation.
Executive priority
Address this in normal vulnerability management unless Garoon is internet-facing or widely used internally, in which case accelerate review. The business concern is potential browser-side compromise of users interacting with bulletin content, but the provided evidence does not support emergency active-exploitation handling.
Technical view
The CVE record describes XSS in Cybozu Garoon 4.0.0 through 5.0.2, affecting Bulletin. The vector is unspecified, and no CWE or CVSS metrics are included in the provided bundle. KEV status is false, so active exploitation is not established by the supplied evidence.
Likely exposure
Exposure is limited to organizations running Cybozu Garoon versions 4.0.0 through 5.0.2 with the Bulletin feature reachable by users or remote attackers. The source bundle does not state whether authentication is required.
Exploitation context
The sources describe remote script injection but do not provide technical vectors, prerequisites, proof of concept, or evidence of exploitation in the wild. Treat this as a plausible user-session risk, not a confirmed active campaign.
Researcher notes
Key gaps are the unspecified vector, absent CVSS, absent CWE, and no provided fixed-version detail in the bundle. Validation should focus on version exposure, Bulletin reachability, vendor advisory confirmation, and safe testing of input/output handling without weaponizing XSS behavior.
Mitigation direction
- Inventory Cybozu Garoon deployments and identify versions from 4.0.0 through 5.0.2.
- Review Cybozu and JVN advisories for vendor-provided updates or workarounds.
- Prioritize remediation for internet-facing or broadly accessible Garoon instances.
- Restrict unnecessary access to the Bulletin feature while vendor guidance is reviewed.
- Monitor bulletin content and user reports for suspicious script-like behavior.
Validation and detection
- Confirm whether any Garoon instance runs an affected version.
- Verify whether the Bulletin feature is enabled and reachable.
- Check vendor advisory status before declaring remediation complete.
- Review application logs for unusual bulletin edits or suspicious content.
- Perform authorized application security testing without using production user sessions.
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-2021-20765 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.