CVE-2021-20123 DrayTek VigorConnect: file path flaw
In plain words: The program can be tricked into reading or writing files outside the folder it should stay in. Leaks files such as passwords and settings, or overwrites important ones.
Confirmed exploited by CISA on · US federal patch deadline Sep 24, 2024
What to do
- Install DrayTek's security update for VigorConnect. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Patch edge devices first — attackers often start scanning for them within hours of a fix.
- Never expose the device's admin page to the internet.
- After patching a device that was exposed, follow the vendor's compromise checks, end active sessions and change passwords.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: They face the internet and guard the whole network, so a flaw here can hand attackers a way in — and these devices usually run no antivirus, so break-ins go unnoticed.
The details
- Official name
- Draytek VigorConnect Path Traversal Vulnerability
- Product
- DrayTek VigorConnect
- CISA description
- 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.
- Type of flaw
- File path flaw (CWE-22)
- Confirmed exploited
- Sep 3, 2024
- US federal patch deadline
- Sep 24, 2024
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Answering about CVE-2021-20123 ·
Questions about CVE-2021-20123
Is CVE-2021-20123 being exploited?
Yes. CISA added CVE-2021-20123 to its Known Exploited Vulnerabilities catalog on Sep 3, 2024, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2021-20123?
Install DrayTek's security update for VigorConnect. If no update exists, follow the vendor's workaround or stop using the product until one ships. Patch edge devices first — attackers often start scanning for them within hours of a fix.
Am I affected by CVE-2021-20123?
Only if you use DrayTek VigorConnect. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.