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CVE-2025-34237VulnerabilityPublished Updated

CVE-2025-34237: Advantech WebAccess/VPN · XSS or 'Cross-site Scripting'

Affects Advantech WebAccess/VPNSource CVE Database V5

0

Not known to be exploited · CVSS 6.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 Nov 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Affected software

ProductAffectedFixed in
Advantech WebAccess/VPNAffected
  • =0
Fixed in–

AI-suggested

European organizations should immediately assess their use of Advantech WebAccess/VPN and verify the version in deployment. Upgrading to version 1.1.5 or later, once available, is the most effective mitigation. In the absence of an official patch, organizations should implement strict input validation and output encoding on all user-supplied data fields, especially those related to VPN client management interfaces. Employ web application firewalls (WAFs) with rules to detect and block XSS payloads targeting the affected endpoints. Restrict administrative access to the VPN management interface via network segmentation and IP whitelisting to limit exposure. Conduct regular security audits and monitoring for anomalous activities or unexpected script injections. Educate users and administrators about the risks of interacting with untrusted inputs and the importance of reporting suspicious behavior. Additionally, consider disabling or restricting features that allow user input in the vulnerable function until a patch is applied. Logging and alerting on input anomalies can provide early detection of exploitation attempts.

Description

Advantech WebAccess/VPN versions prior to 1.1.5 contain a stored cross-site scripting (XSS) vulnerability via StandaloneVpnClientsController.addStandaloneVpnClientAction(). Insufficient validation or escaping of user-supplied input may allow an attacker to inject and execute arbitrary script in the context of a victim's browser.

References

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