What is CVE-2021-20874?

CVE-2021-20874 is a high-severity vulnerability in Groupsession, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 7.5/10. Published 2021-12-24.

How severe is CVE-2021-20874?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Groupsession

CVE-2021-20874

Incorrect permission assignment for critical resource vulnerability in GroupSession Free edition ver5.1.1 and earlier, GroupSession byCloud ver5.1.1 and earlier, and GroupSession ZION ver5.1.1 and earlier allows a remote unauthenticated attacker to access arbitrary files on the server and obtain sensitive information via unspecified vectors.

Published 2021-12-24 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.013 (69.2th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 69th percentile — 69.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Groupsession
Japan Total System Co.,ltd. Groupsession Free Edition, Bycloud, Zion — versions GroupSession Free edition ver5.1.1 and earlier, GroupSession byCloud ver5.1.1 and earlier, and GroupSession ZION ver5.1.1 and earlier

Weakness classification (CWE)

CWE-732 — Incorrect Permission Assignment for Critical Resource

References

groupsession.jp/info/info-news/security20211220 (Vendor Advisory)
jvn.jp/en/jp/JVN79798166/index.html (Third Party Advisory)

Frequently asked questions

What is CVE-2021-20874?: CVE-2021-20874 is a high-severity vulnerability in Groupsession, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 7.5/10. Published 2021-12-24.
How severe is CVE-2021-20874?: High severity. CVSS v3 base score is 7.5 out of 10.