An arbitrary file upload and directory traversal vulnerability exists in the file upload functionality of DownloadFileServlet in Draytek Vi…

published 2021-10-13 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-7582

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 3.9%; EPSS 3.9% chance of exploitation in 30 days, percentile 90%
public exploits: 0; none known

An arbitrary file upload and directory traversal vulnerability exists in the file upload functionality of DownloadFileServlet in Draytek VigorConnect 1.6.0-B3. An unauthenticated attacker could leverage this vulnerability to upload files to any location on the target operating system with root privileges.

Exploit prediction

3.95% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

tenable.com https://www.tenable.com/security/research/tra-2021-42 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	10.0	AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected products

n/a Draytek VigorConnect

Classification

Weakness

CWE-22 Improper Limitation of a Pathname to a Restricted Directory
CWE-434 Unrestricted Upload of File with Dangerous Type

References

tenable.com /security/research/tra-2021-42
exploit, third-party-advisory

Sources

CVE List CVE-2021-20125
NVD CVE-2021-20125

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary