CVE-2021-20123: Draytek VigorConnect Path Traversal Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 1,056 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 89.7%
EPSS score, percentile 99.8 of all scored records
- How severe?
- 7.5 High
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA deadline . Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 1.6.0-B3
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
What to do
Required action, set by CISA
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
CISA due date for this action: .
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://www.draytek.com/about/security-advisory/vigorconnect-software-security-vulnerability-(cve-2021-20123-cve-2021-20129
- https://nvd.nist.gov/vuln/detail/CVE-2021-20123
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 1.6.0-B3 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
About this vulnerability
Draytek VigorConnect contains a path traversal vulnerability in the DownloadFileServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges.
Summary: CISA's KEV catalog, as of .
- CISA added CVE-2021-20123 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Sep 2024.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 24 Sep 2024.
- The CVE record was published on 13 Oct 2021, 1,056 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 7.5 (High), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 89.7% (percentile 99.8), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
Weakness
- CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| Added to CISA KEV | |
| CISA due date for the required action | |
| CVE record last updated |
References
More exploited DrayTek vulnerabilities
- CVE-2024-12987: DrayTek Vigor Routers OS Command Injection Vulnerability
- CVE-2020-15415: DrayTek Multiple Vigor Routers OS Command Injection Vulnerability
- CVE-2021-20124: Draytek VigorConnect Path Traversal Vulnerability
- CVE-2020-8515: Multiple DrayTek Vigor Routers Web Management Page Vulnerability