CVE-2021-20123 — Vigorconnect
HIGHCVE-2021-20123 is a high-severity (CVSS 7.5) Path Traversal vulnerability in draytek vigorconnect. It is in CISA's Known Exploited Vulnerabilities catalog (added 2024-09-03) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.
A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of the DownloadFileServlet endpoint. An unauthenticated attacker could…
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2024-09-03. Federal agencies were required to remediate by 2024-09-24.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2021-20123.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-20123 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.
Description
A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of the DownloadFileServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges.
Affected Products
vigorconnectdraytekResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every draytek vigorconnect deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2021-20123 yet — track the draytek vigorconnect advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
How to detect CVE-2021-20123
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2021-20123 -u https://target- Template
- Draytek VigorConnect 1.6.0-B - Local File Inclusion
- Severity
- high
- Impact
- Successful exploitation of this vulnerability could allow an attacker to read sensitive files on the server, potentially leading to unauthorized access or information disclosure.
- Remediation
- Apply the latest security patches or updates provided by the vendor to fix the LFI vulnerability in Draytek VigorConnect 1.6.0-B.
Template by ProjectDiscovery nuclei-templates (0x_Akoko), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2021-20123 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.