CVE-2021-20631Network attack vector

Custom App display interruption via malformed data

Published Mar 18, 2021 · Updated Aug 3, 2024

Improper input validation in Cybozu Office 10.0.0 through 10.8.4 allows remote authenticated users to alter Custom App data. Cybozu has not published the affected input-processing locus or the crafted values that pass validation. A valid login is required, and altered records can prevent related Custom App content from being displayed.

CVSS severity4.3
Medium
EPSS probability0.74%
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 Office 10.0.0 through 10.8.4 allows remote authenticated users to alter Custom App data. Cybozu has not published the affected input-processing locus or the crafted values that pass validation. A valid login is required, and altered records can prevent related Custom App content from being displayed.

The record

CVE
CVE-2021-20631
Published
Mar 18, 2021
Updated
Aug 3, 2024
Vendor
Cybozu
Product
Cybozu Office
Classifications
CWE-20, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 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=10.0.0 to 10.8.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cybozu · Cybozu Officeversion=10.0.0 to 10.8.4

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
4.0JPCERT/CCAV:N/AC:L/Au:S/C:N/I:N/A:P
4.3JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1565.001Stored Data Manipulation

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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