What is CVE-2020-18670?

CVE-2020-18670 is a medium-severity vulnerability in Roundcube Webmail, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-06-24.

How severe is CVE-2020-18670?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Roundcube Webmail

CVE-2020-18670

Cross Site Scripting (XSS) vulneraibility in Roundcube mail .4.4 via database host and user in /installer/test.php.

Vulnerability class: XSS (Cross-Site Scripting)

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

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.009 (58.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Roundcube Webmail — versions 1.4.4

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/roundcube/roundcubemail/issues/7406 (Patch, Third Party Advisory)
roundcube.net/news/2020/06/02/security-updates-1.4.5-and-1.3.12 (Patch, Vendor Advisory)
lorexxar.cn/2020/06/10/roundcube-mail-xss/ (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2020-18670?: CVE-2020-18670 is a medium-severity vulnerability in Roundcube Webmail, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-06-24.
How severe is CVE-2020-18670?: Medium severity. CVSS v3 base score is 5.4 out of 10.