How to check if you are exposed to CVE-2021-20123
- Find every DrayTek VigorConnect system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
- Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
- Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2021-20123.
US federal agencies had to fix this by 2024-09-24. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.
Affected versions
Versions the National Vulnerability Database lists as vulnerable to CVE-2021-20123. Check the vendor advisory for the exact fixed builds before you sign anything off.
| Product | Vulnerable versions |
|---|---|
| DrayTek Vigorconnect | 1.6.0-beta3 |
Timeline
- · Published in the National Vulnerability Database
- · Added to CISA's Known Exploited Vulnerabilities catalog, 1,056 days after it was published
- · Fix-by date for US federal agencies, passed 768 days ago
Vendor advisories and fixes
Weakness type
More exploited DrayTek vulnerabilities
CISA lists 5 exploited DrayTek vulnerabilities. The closest matches:
- CVE-2021-20124Draytek VigorConnect Path Traversal Vulnerability Added 2024-09-03
- CVE-2024-12987DrayTek Vigor Routers OS Command Injection VulnerabilityAdded 2025-05-15
- CVE-2020-15415DrayTek Multiple Vigor Routers OS Command Injection VulnerabilityAdded 2024-09-30
- CVE-2020-8515Multiple DrayTek Vigor Routers Web Management Page VulnerabilityAdded 2021-11-03
Keep going
Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.