What is CVE-2020-5539?

CVE-2020-5539 is a medium-severity vulnerability in Grandit, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2020-03-02.

How severe is CVE-2020-5539?

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

Auth bypass in Grandit

CVE-2020-5539

GRANDIT Ver.1.6, Ver.2.0, Ver.2.1, Ver.2.2, Ver.2.3, and Ver.3.0 do not properly manage sessions, which allows remote attackers to impersonate an arbitrary user and then alter or disclose the information via unspecified vectors.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2020-03-02 · last modified 2026-06-17.

CVSS v3 metric

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

EPSS exploit prediction

EPSS: 0.008 (56.4th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.4% 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

Grandit — versions 1.6, 2.0, 2.1
Grandit Corporation — versions Ver.1.6, Ver.2.0, Ver.2.1, Ver.2.2, Ver.2.3, and Ver.3.0

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

jvn.jp/en/jp/JVN73472345/index.html (Third Party Advisory)
www.grandit.jp/etc/20200228_letter.pdf (Vendor Advisory)

Frequently asked questions

What is CVE-2020-5539?: CVE-2020-5539 is a medium-severity vulnerability in Grandit, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2020-03-02.
How severe is CVE-2020-5539?: Medium severity. CVSS v3 base score is 6.5 out of 10.