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Improper Input ValidationWeakness · CWE-20

CVE-2025-34047

HIGH · 8.7 CVSS v4.0 Published 2025-06-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
96/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A path traversal vulnerability exists in the Leadsec SSL VPN (formerly Lenovo NetGuard), allowing unauthenticated attackers to read arbitrary files on the underlying system via the ostype parameter in the /vpn/user/download/client endpoint. This flaw arises from insufficient input sanitation, enabling traversal sequences to escape the intended directory and access sensitive files. Exploitation evidence was observed by the Shadowserver Foundation on 2025-02-05 UTC.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A path traversal vulnerability in Leadsec SSL VPN (formerly Lenovo NetGuard) allows unauthenticated attackers to read arbitrary files on the underlying system through the ostype parameter in the /vpn/user/download/client endpoint. Insufficient input sanitization permits traversal sequences (e.g., ../../) to escape the intended directory and access sensitive files. The vulnerability has been actively exploited in the wild.

MitigationApply vendor patches immediately; if unavailable, restrict access to the vulnerable endpoint via network filtering or WAF rules that block traversal patterns, and consider disabling the affected functionality until a fix is available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Leadsec SSL VPN installation
    Check for running processes named 'sslvpn', 'leadsec', or 'netguard', or look for installation directories containing these names in /opt, /usr/local, or C:\Program Files
    Affected if The product is installed on the system
  2. Verify the vulnerable endpoint exists
    Attempt to access the /vpn/user/download/client endpoint via HTTP/HTTPS on the VPN server (e.g., curl https://<vpn-host>/vpn/user/download/client)
    Affected if The endpoint responds with any content, indicating it is exposed
  3. Confirm traversal is possible
    Send a request with a traversal pattern in the ostype parameter (e.g., /vpn/user/download/client?ostype=../../../../etc/passwd) and check if file contents are returned
    Affected if The response contains contents of files outside the intended directory (e.g., /etc/passwd contents on Linux or C:\Windows\win.ini on Windows)
  4. Check for evidence of exploitation
    Review web server access logs for patterns like '../' or '..\' in ostype parameter values, particularly from external IP addresses
    Affected if Log entries show traversal attempts with the ostype parameter
  5. Assess network exposure
    Determine if the /vpn/user/download/client endpoint is accessible from untrusted networks (Internet) versus being restricted to internal networks or VPN clients only
    Affected if The endpoint is reachable from untrusted/external networks without authentication

If Leadsec SSL VPN is installed, the vulnerable endpoint is exposed, and traversal via the ostype parameter returns arbitrary file contents, the environment is affected by CVE-2025-34047.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor patches immediately; if unavailable, restrict access to the vulnerable endpoint via network filtering or WAF rules that block traversal patterns, and consider disabling the affected functionality until a fix is available.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-34047 in production — separate from our analysis above.

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What this is

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