CVE-2021-20123
Path Traversal in Draytek Vigorconnect 1.6.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NSummary
CVE-2021-20123 is a high-severity Path Traversal (CWE-22) vulnerability in Draytek Vigorconnect. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 0.5% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2021-20123 is a path traversal vulnerability, tracked as CWE-22, that affects Draytek VigorConnect version 1.6.0-B3. The flaw exists in the DownloadFileServlet endpoint used for file downloads and permits access to arbitrary files on the underlying operating system.
An unauthenticated remote attacker can exploit the issue over the network without any user interaction or credentials. Successful exploitation grants the ability to read arbitrary files with root privileges, producing a high confidentiality impact consistent with the assigned CVSS 3.1 score of 7.5.
The vulnerability appears in CISA's Known Exploited Vulnerabilities catalog and is detailed in Tenable research advisory TRA-2021-42, confirming that mitigation should follow vendor guidance for upgrading or restricting access to the affected endpoint.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-7580
Vulnerability Data
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.
- CWE(s)
- KEV Date Added
- 03 September 2024
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.3.2
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Validates pathnames and filenames to prevent traversal outside intended directories.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Patching/maintenance can remediate known path-traversal flaws in deployed software (partial prevention of exploitability) but does nothing to stop the coding defect from being introduced in the first place.
PR.AA-05 defines and reviews access policies but does not address code-level pathname neutralization, so neither direction prevents CWE-22.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development catches path traversal via static/dynamic analysis.
Secure SDLC mandates input validation and path sanitization that directly prevent path traversal.
Application security requirements include rules for safe file handling and canonicalization.
Secure architecture principles require least-privilege file access and directory isolation.
Secure coding standards explicitly forbid unsafe path construction and mandate safe APIs.
Information access restriction limits which files an application may read or write.