CVE-2021-20628Network attack vector

Arbitrary script execution via undisclosed Address Book input

Published Mar 18, 2021 · Updated Aug 3, 2024

Cross-site scripting in the Address Book of Cybozu Office 10.0.0 through 10.8.4 allows remote attackers to execute script in users' browsers. Cybozu has not published the vulnerable input or processing path and deliberately withholds reproduction steps. Exploitation requires a user to interact with affected Address Book content in Mozilla Firefox, where the script runs in the application's browser context.

CVSS severity6.1
Medium
EPSS probability0.81%
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 Address Book of Cybozu Office 10.0.0 through 10.8.4 allows remote attackers to execute script in users' browsers. Cybozu has not published the vulnerable input or processing path and deliberately withholds reproduction steps. Exploitation requires a user to interact with affected Address Book content in Mozilla Firefox, where the script runs in the application's browser context.

The record

CVE
CVE-2021-20628
Published
Mar 18, 2021
Updated
Aug 3, 2024
Vendor
Cybozu
Product
Cybozu Office
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

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 privilegesunauthenticated

What is affected?

Cybozu · Cybozu Officeversion=10.0.0 to 10.8.4

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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