What is CVE-2021-20628?

CVE-2021-20628 is a medium-severity vulnerability in Cybozu Office, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-03-18.

How severe is CVE-2021-20628?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Cybozu Office

CVE-2021-20628

Cross-site scripting vulnerability in Address Book of Cybozu Office 10.0.0 to 10.8.4 allows remote attackers to inject an arbitrary script via unspecified vectors. Note that this vulnerability occurs only when using Mozilla Firefox.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-03-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.2th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Cybozu Office
Cybozu, Inc. Cybozu Office — versions 10.0.0 to 10.8.4
Mozilla Firefox

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

jvn.jp/en/jp/JVN45797538/index.html (Third Party Advisory)
kb.cybozu.support/article/36868/ (Vendor Advisory)

Frequently asked questions

What is CVE-2021-20628?: CVE-2021-20628 is a medium-severity vulnerability in Cybozu Office, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-03-18.
How severe is CVE-2021-20628?: Medium severity. CVSS v3 base score is 6.1 out of 10.