IRONSMITHINTEL
HIGHCVSS7.5
|
Actively Exploited
|CISA KEV|CVE-2021-20124|Auth: none — unauthenticated|Reboot: required|Manual only

Draytek VigorConnect Path Traversal Vulnerability

Draytek VigorConnect contains a path traversal vulnerability in the file download functionality of the WebServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges.

Published Oct 13, 2021 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss. Federal agencies are required to remediate by 2024-09-24 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Path Traversal (CWE-22) vulnerability in DrayTek VigorConnect. A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of the WebServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

📧

Phishing link

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running vigorconnect: 1.6.0
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: https://www.tenable.com/security/research/tra-2021-42

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

References

    1
    Vendor advisory: https://www.draytek.com/about/security-advisory/vigorconnect-software-security-vulnerability-(cve-2021-20123-cve-2021-20129)
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2021-20124
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20124
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