What is CVE-2021-20631?

CVE-2021-20631 is a medium-severity vulnerability in Cybozu Office, classified under Improper Input Validation. CVSS score: 6.5/10. Published 2021-03-18.

How severe is CVE-2021-20631?

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

Improper input validation in Cybozu Office

CVE-2021-20631

Improper input validation vulnerability in Custom App of Cybozu Office 10.0.0 to 10.8.4 allows authenticated attacker to alter the data of Custom App via unspecified vectors.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2021-03-18 · 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:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.007 (52.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 52.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

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

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

jvn.jp/en/jp/JVN45797538/index.html (Third Party Advisory)
kb.cybozu.support/article/36871/ (Vendor Advisory)

Frequently asked questions

What is CVE-2021-20631?: CVE-2021-20631 is a medium-severity vulnerability in Cybozu Office, classified under Improper Input Validation. CVSS score: 6.5/10. Published 2021-03-18.
How severe is CVE-2021-20631?: Medium severity. CVSS v3 base score is 6.5 out of 10.