Security readout for executives and security teams
Plain-English summary
Draytek VigorConnect 1.6.0-B3 has an unauthenticated file download flaw that could expose files from the host operating system. Because access is reported as root-level and CISA lists it in KEV, treat exposed instances as urgent.
Executive priority
Prioritize remediation for any reachable VigorConnect 1.6.0-B3 system. The issue enables unauthenticated data theft from the server, and CISA KEV status raises business urgency.
Technical view
CVE-2021-20124 is a CWE-22 local file inclusion/path traversal issue in VigorConnect 1.6.0-B3 WebServlet download functionality. Network attackers need no credentials or user interaction and can read arbitrary operating-system files. Impact is confidentiality only in CVSS, with score 7.5.
Likely exposure
Exposure is likely where Draytek VigorConnect 1.6.0-B3 is deployed and its web interface is reachable by untrusted networks. Public internet exposure materially increases urgency.
Exploitation context
CISA KEV inclusion means known exploitation is recognized by CISA. The provided bundle does not include exploit volume, attacker identity, or whether exploitation is current.
Researcher notes
The source bundle identifies only Draytek VigorConnect 1.6.0-B3. Evidence supports arbitrary file read with root privileges through WebServlet download handling. No source-provided fixed version, workaround, exploit chain, or post-exploitation detail is included here.
Mitigation direction
- Inventory Draytek VigorConnect deployments and confirm whether version 1.6.0-B3 is present.
- Remove public access to the VigorConnect web interface immediately.
- Restrict management access to trusted admin networks or VPN only.
- Check DrayTek/Tenable guidance for fixed releases; the provided sources do not name a fixed version.
- If exposure is suspected, rotate secrets stored on affected hosts.
Validation and detection
- Confirm product name and version from asset inventory or administrative records.
- Verify the VigorConnect web interface is not reachable from untrusted networks.
- Review server logs for unusual file download activity against WebServlet.
- Check whether CISA KEV remediation deadlines apply to your organization.
- Document compensating controls if an immediate upgrade is unavailable.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-20124 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.tenable.com/security/research/tra-2021-42CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20124CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.