CVE-2021-20803Network attack vector

Authenticated management data alteration via authorization bypass

Published Oct 13, 2021 · Updated Aug 3, 2024

Incorrect authorization in Cybozu Remote Service 3.1.8 through 3.1.9 allows remote authenticated users to alter management-screen data. The affected management-screen operation fails to enforce its intended restriction, but Cybozu has not disclosed the request handler or authorization check involved. Any user able to log in can reach the flaw; documented consequences are limited to management-data changes and low availability impact.

CVSS severity5.4
Medium
EPSS probability0.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Cybozu Remote Service 3.1.8 through 3.1.9 allows remote authenticated users to alter management-screen data. The affected management-screen operation fails to enforce its intended restriction, but Cybozu has not disclosed the request handler or authorization check involved. Any user able to log in can reach the flaw; documented consequences are limited to management-data changes and low availability impact.

The record

CVE
CVE-2021-20803
Published
Oct 13, 2021
Updated
Aug 3, 2024
Vendor
Cybozu
Product
Cybozu Remote Service
Classifications
CWE-863
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 13, 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=3.1.8 to 3.1.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cybozu · Cybozu Remote Serviceversion=3.1.8 to 3.1.9

Published CVSS scores

5.4JPCERT/CC and IPA JVNCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:N
5.5JPCERT/CC and IPA JVNAV:N/AC:L/Au:S/C:N/I:P/A:P
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

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-863Incorrect Authorization

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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