What is CVE-2021-20801?

CVE-2021-20801 is a medium-severity vulnerability in Cybozu Remote Service Manager, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 6.5/10. Published 2021-10-13.

How severe is CVE-2021-20801?

Medium severity. CVSS v3 base score is 6.5 out of 10.

XXE in Cybozu Remote Service Manager

CVE-2021-20801

Cybozu Remote Service 3.1.8 to 3.1.9 allows a remote authenticated attacker to conduct XML External Entity (XXE) attacks and obtain the information stored in the product via unspecified vectors. This issue occurs only when using Mozilla Firefox.

Vulnerability class: XXE (XML External Entity)

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

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.011 (63.3th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 63.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · 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-611 — Improper Restriction of XML External Entity Reference (XXE)

References

jvn.jp/en/jp/JVN52694228/index.html (Third Party Advisory)
kb.cybozu.support/article/37423 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-20801?: CVE-2021-20801 is a medium-severity vulnerability in Cybozu Remote Service Manager, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 6.5/10. Published 2021-10-13.
How severe is CVE-2021-20801?: Medium severity. CVSS v3 base score is 6.5 out of 10.