CVE-2021-20764Network attack vector

Unauthorized attachment data disclosure

Published Aug 18, 2021 · Updated Aug 3, 2024

Improper input validation in Cybozu Garoon 4.0.0 through 5.0.2 allows remote attackers to read attachment data through crafted requests. Cybozu and JVN identify the Attaching Files component but do not disclose which input is accepted incorrectly or how it selects unauthorized file data. Exploitation requires a user to interact with attacker-supplied content, and the documented consequence is attachment disclosure only.

CVSS severity4.3
Medium
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Cybozu Garoon 4.0.0 through 5.0.2 allows remote attackers to read attachment data through crafted requests. Cybozu and JVN identify the Attaching Files component but do not disclose which input is accepted incorrectly or how it selects unauthorized file data. Exploitation requires a user to interact with attacker-supplied content, and the documented consequence is attachment disclosure only.

The record

CVE
CVE-2021-20764
Published
Aug 18, 2021
Updated
Aug 3, 2024
Vendor
Cybozu
Product
Garoon
Classifications
CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.0.0 to 5.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cybozu · Garoonversion=4.0.0 to 5.0.2

Published CVSS scores

2.6JVNAV:N/AC:H/Au:N/C:P/I:N/A:N
4.3JVNCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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