What is CVE-2021-20743?

CVE-2021-20743 is a medium-severity vulnerability in Ec-Cube, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-06-22.

How severe is CVE-2021-20743?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Ec-Cube

CVE-2021-20743

Cross-site scripting vulnerability in EC-CUBE Email newsletters management plugin (for EC-CUBE 3.0 series) versions prior to version 1.0.4 allows a remote attacker to inject an arbitrary script by leading a user to a specially crafted page and to perform a specific operation.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-06-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (53.4th percentile), scored 2026-10-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.4% 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

Ec-Cube
Ec-Cube Email Newsletters Management
Ec-Cube Co.,ltd. Email Newsletters Management Plugin (For 3.0 Series) — versions versions prior to version 1.0.4

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

jvn.jp/en/jp/JVN57524494/index.html (Third Party Advisory)
www.ec-cube.net/products/detail.php (Product)

Frequently asked questions

What is CVE-2021-20743?: CVE-2021-20743 is a medium-severity vulnerability in Ec-Cube, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-06-22.
How severe is CVE-2021-20743?: Medium severity. CVSS v3 base score is 6.1 out of 10.