Threats / DrayTek / CVE-2021-20124
CVE-2021-20124
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
DrayTek VigorConnect vulnerability
DrayTek VigorConnect contains a path traversal vulnerability in file download functionality that allows unauthenticated attackers to download arbitrary files with root privileges.
Verdict
Today item — known-exploited.
An unauthenticated remote attacker can exploit path traversal in the WebServlet endpoint to access sensitive files on the system. The vulnerability is actively exploited in the wild and carries high severity due to lack of authentication requirements and root-level file access.
CISA KEV Yes · 2024-09-034EPSS 0.96308 (verify live)5CVSS 7.5 (CISA)3CISA SSVC Exploitation: active · Automatable: yes · Impact: partial3Exploit Public PoC / detection · nuclei template12
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
269 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2024-09-03).
Probability (EPSS)
EPSS 0.96308 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) · Affected: DrayTek, VigorConnect. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-22 Path Traversal — weakness family: Path traversal / file.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: partialCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 1056 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious file path using traversal sequences to bypass directory restrictions in the download endpoint.
Business
Sensitive system files become accessible to external threat actors without credentials.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I retrieve configuration files, private keys, or other root-owned data from the compromised appliance.
Business
Confidential credentials and system secrets are exposed, enabling lateral movement and further compromise.
3
Lateral reach — past segmentation narrative 3
Attacker
I use extracted credentials or system information to establish persistent access or pivot to connected infrastructure.
Business
The organization's network perimeter is breached, with potential for widespread system compromise and data exfiltration.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by tenableCNA
Credited with finding itNo finder is named in the public CVE record or the scanned vendor advisory — attribution scoped to the sources checked.
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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