CVE-2021-42703Network attack vector

Session theft via undisclosed cross-site scripting

Published Nov 15, 2021 · Updated Sep 17, 2024

Cross-site scripting in Advantech WebAccess/HMI Designer 2.1.11.0 and earlier allows remote attackers to run script in a user's browser. The public advisory does not identify the input field, request path, or rendering operation that accepts and returns the malicious JavaScript. Exploitation requires user interaction and can expose cookie or session tokens, redirect the user, and trigger unintended browser actions.

CVSS severity6.1
Medium
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Advantech WebAccess/HMI Designer 2.1.11.0 and earlier allows remote attackers to run script in a user's browser. The public advisory does not identify the input field, request path, or rendering operation that accepts and returns the malicious JavaScript. Exploitation requires user interaction and can expose cookie or session tokens, redirect the user, and trigger unintended browser actions.

The record

CVE
CVE-2021-42703
Published
Nov 15, 2021
Updated
Sep 17, 2024
Vendor
Advantech
Product
WebAccess/HMI Designer
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=All versions <=2.1.11.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Advantech · WebAccess/HMI Designerversion=All versions <=2.1.11.0

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.4ICS-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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