What is CVE-2021-42703?

CVE-2021-42703 is a medium-severity vulnerability in Advantech Hmi Designer, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-11-15.

How severe is CVE-2021-42703?

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

XSS in Advantech Hmi Designer

CVE-2021-42703

This vulnerability could allow an attacker to send malicious Javascript code resulting in hijacking of the user’s cookie/session tokens, redirecting the user to a malicious webpage, and performing unintended browser action.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-11-15 · last modified 2026-06-17.

CVSS v3 metric

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

EPSS exploit prediction

EPSS: 0.006 (48.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 48.7% 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

Advantech Hmi Designer — versions All versions
Advantech Webaccess Hmi Designer

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

us-cert.cisa.gov/ics/advisories/icsa-21-173-01 (US Government Resource, Third Party Advisory)

Frequently asked questions

What is CVE-2021-42703?: CVE-2021-42703 is a medium-severity vulnerability in Advantech Hmi Designer, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-11-15.
How severe is CVE-2021-42703?: Medium severity. CVSS v3 base score is 5.4 out of 10.