CVE-2021-20805Network attack vector

Authenticated script execution via management-screen input

Published Oct 13, 2021 · Updated Aug 3, 2024

Cross-site scripting in the Cybozu Remote Service 3.1.7 through 3.1.9 management screen allows remote authenticated users to inject script. Cybozu has not published the affected parameter or the management-screen operation that fails to neutralize untrusted input, and it withholds reproduction steps. Exploitation requires low-privileged product authentication and a logged-in user to interact with the injected content, allowing browser-session data disclosure or modification but no service interruption.

CVSS severity5.4
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in the Cybozu Remote Service 3.1.7 through 3.1.9 management screen allows remote authenticated users to inject script. Cybozu has not published the affected parameter or the management-screen operation that fails to neutralize untrusted input, and it withholds reproduction steps. Exploitation requires low-privileged product authentication and a logged-in user to interact with the injected content, allowing browser-session data disclosure or modification but no service interruption.

The record

CVE
CVE-2021-20805
Published
Oct 13, 2021
Updated
Aug 3, 2024
Vendor
Cybozu
Product
Cybozu Remote Service
Classifications
CWE-79, T1059.007
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=3.1.7 to 3.1.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cybozu · Cybozu Remote Serviceversion=3.1.7 to 3.1.9

Published CVSS scores

5.4JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5JPCERT/CCAV:N/AC:M/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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

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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