CVE-2017-20123Public exploit

Local SYSTEM execution via OpenVPN path traversal

Published Jun 30, 2022 · Updated Apr 15, 2025

Path traversal in Viscosity 1.6.7 for Windows allows local users to execute arbitrary code with SYSTEM privileges. ViscosityService's startOpenVPN method appends the caller-controlled openVPNVer value to an executable path without rejecting traversal segments, allowing a user-writable OpenVPN copy and lzo2.dll to run as SYSTEM. Exploitation requires local access and code injection into the signed Viscosity process to reach its named pipe; VPN connection security is unaffected.

CVSS severity8.8
High
EPSS probability1.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Viscosity 1.6.7 for Windows allows local users to execute arbitrary code with SYSTEM privileges. ViscosityService's startOpenVPN method appends the caller-controlled openVPNVer value to an executable path without rejecting traversal segments, allowing a user-writable OpenVPN copy and lzo2.dll to run as SYSTEM. Exploitation requires local access and code injection into the signed Viscosity process to reach its named pipe; VPN connection security is unaffected.

The record

CVE
CVE-2017-20123
Published
Jun 30, 2022
Updated
Apr 15, 2025
Vendor
SparkLabs
Product
Viscosity
Classifications
CWE-426, CWE-427, T1574.002, T1055
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 30, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record 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=1.6.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

SparkLabs · Viscosityversion=1.6.7

Published CVSS scores

7.8NISTCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.9NISTAV:L/AC:M/Au:N/C:C/I:C/A:C
8.8VulDBCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-426Untrusted Search Path
CWE-427Uncontrolled Search Path Element
T1574.002DLL Side-Loading
T1055Process Injection

Public exploit references

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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