What is CVE-2021-20128?

CVE-2021-20128 is a medium-severity vulnerability in Draytek Vigorconnect, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-10-13.

How severe is CVE-2021-20128?

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

XSS in Draytek Vigorconnect

CVE-2021-20128

The Profile Name field in the floor plan (Network Menu) page in Draytek VigorConnect 1.6.0-B3 was found to be vulnerable to stored XSS, as user input is not properly sanitized.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-10-13 · 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: 0.006 (44.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 44.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Draytek Vigorconnect — versions 1.6.0
Draytek Vigorconnect — versions 1.6.0-B3

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.tenable.com/security/research/tra-2021-42 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-20128?: CVE-2021-20128 is a medium-severity vulnerability in Draytek Vigorconnect, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-10-13.
How severe is CVE-2021-20128?: Medium severity. CVSS v3 base score is 5.4 out of 10.