What is CVE-2021-20799?

CVE-2021-20799 is a medium-severity vulnerability in Cybozu Remote Service Manager, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-10-13.

How severe is CVE-2021-20799?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Cybozu Remote Service Manager

CVE-2021-20799

Cross-site scripting vulnerability in the management screen of Cybozu Remote Service 3.1.8 to 3.1.9 allows a remote authenticated attacker to inject an arbitrary script via unspecified vectors.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-10-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (47.0th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 47.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Cybozu Remote Service Manager — versions 3.1.8, 3.1.9
Cybozu, Inc. Cybozu Remote Service — versions 3.1.8 to 3.1.9

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

jvn.jp/en/jp/JVN52694228/index.html (Third Party Advisory)
kb.cybozu.support/article/37425 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-20799?: CVE-2021-20799 is a medium-severity vulnerability in Cybozu Remote Service Manager, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-10-13.
How severe is CVE-2021-20799?: Medium severity. CVSS v3 base score is 5.4 out of 10.