What is CVE-2021-20766?

CVE-2021-20766 is a medium-severity vulnerability in Cybozu Garoon, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-08-18.

How severe is CVE-2021-20766?

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

XSS in Cybozu Garoon

CVE-2021-20766

Cross-site scripting vulnerability in Message of Cybozu Garoon 4.0.0 to 5.0.2 allows a remote attacker to inject an arbitrary script via unspecified vectors.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-08-18 · 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 (53.4th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.4% 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 Garoon
Cybozu, Inc. Cybozu Garoon — versions 4.0.0 to 5.0.2

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

cs.cybozu.co.jp/2021/007206.html (Vendor Advisory)
jvn.jp/en/jp/JVN54794245/index.html (Third Party Advisory)

Frequently asked questions

What is CVE-2021-20766?: CVE-2021-20766 is a medium-severity vulnerability in Cybozu Garoon, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-08-18.
How severe is CVE-2021-20766?: Medium severity. CVSS v3 base score is 6.1 out of 10.