CVE-2020-12026Network attack vector

Arbitrary file overwrite via unvalidated ViewSrv path

Published May 8, 2020 · Updated Aug 4, 2024

Relative path traversal in Advantech WebAccess/SCADA 8.4.4 and earlier and 9.0.0 allows remote authenticated users to overwrite files. ViewSrv.dll IOCTL 0x0000277d uses an unvalidated user-supplied path in file operations, permitting writes outside application-controlled directories. CISA requires low privileges and user interaction, while ZDI reports no authentication or interaction and Administrator-context code execution.

CVSS severity8.8
High
EPSS probability2.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Relative path traversal in Advantech WebAccess/SCADA 8.4.4 and earlier and 9.0.0 allows remote authenticated users to overwrite files. ViewSrv.dll IOCTL 0x0000277d uses an unvalidated user-supplied path in file operations, permitting writes outside application-controlled directories. CISA requires low privileges and user interaction, while ZDI reports no authentication or interaction and Administrator-context code execution.

The record

CVE
CVE-2020-12026
Published
May 8, 2020
Updated
Aug 4, 2024
Vendor
Advantech
Product
WebAccess/SCADA
Classifications
CWE-22, CWE-23, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 8, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=WebAccess Node Version 8.4.4 and prior, WebAccess Node Version 9.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Advantech · WebAccess/SCADAversion=WebAccess Node Version 8.4.4 and prior, WebAccess Node Version 9.0.0

Published CVSS scores

6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
9.8Zero Day InitiativeCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.0CISACVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-23Relative Path Traversal
T1190Exploit Public-Facing Application

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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