CVE-2025-34237Network attack vector

Stored script execution via unescaped VPN client input

Published Nov 6, 2025 · Updated Nov 6, 2025

Stored XSS in Advantech WebAccess/VPN before 1.1.5 allows remote authenticated users to execute scripts in a victim's browser. StandaloneVpnClientsController.addStandaloneVpnClientAction() stores user-supplied input without sufficient validation or output escaping. Low-privileged access is required to persist the payload, and a victim must view the affected interface; execution is limited to the browser context.

CVSS severity5.4
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Advantech WebAccess/VPN before 1.1.5 allows remote authenticated users to execute scripts in a victim's browser. StandaloneVpnClientsController.addStandaloneVpnClientAction() stores user-supplied input without sufficient validation or output escaping. Low-privileged access is required to persist the payload, and a victim must view the affected interface; execution is limited to the browser context.

The record

CVE
CVE-2025-34237
Published
Nov 6, 2025
Updated
Nov 6, 2025
Vendor
Advantech
Product
WebAccess/VPN
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 6, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 6, 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=0 <1.1.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Advantech · WebAccess/VPNversion=0 <1.1.5

Published CVSS scores

6.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
7.3AdvantechCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

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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