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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 21 Oct 2024.
Vigor3900 FirmwareOperating system · Draytek

CVE-2020-15415

CRITICAL · 9.8 CVSS v3.1 Published 2020-06-30
Fix available
A fix is available. Upgrade to 1.5.1 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
On DrayTek Vigor3900, Vigor2960, and Vigor300B devices before 1.5.1, cgi-bin/mainfunction.cgi/cvmcfgupload allows remote command execution via shell metacharacters in a filename when the text/x-python-script content type is used, a different issue than CVE-2020-14472.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

DrayTek Vigor3900, Vigor2960, and Vigor300B devices before firmware 1.5.1 contain a remote command execution vulnerability in the cvmcfgupload function of cgi-bin/mainfunction.cgi. Attackers can execute arbitrary commands by uploading a file with shell metacharacters in the filename when specifying the text/x-python-script content type.

MitigationUpgrade affected devices to firmware version 1.5.1 or later. If immediate patching is not possible, restrict network access to the admin web interface (port 443/80) to trusted IPs only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Vigor3900 FirmwareOperating system
Affected:< 1.5.1
Vigor2960 FirmwareOperating system
Affected:< 1.5.1
Vigor300b FirmwareOperating system
Affected:< 1.5.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the DrayTek router model
    Access the router web interface or check the device label to confirm the model is a Vigor3900, Vigor2960, or Vigor300B.
    Affected if The device is one of these three models.
  2. Check the installed firmware version
    Log into the router web interface and navigate to System Maintenance > Firmware Upgrade, or check the status page to find the current firmware version.
    Affected if The firmware version is lower than 1.5.1.
  3. Verify the web management interface is accessible
    Confirm that the router's web interface (port 443 or 80) is reachable from the network segment you are checking. The vulnerability exists in the cgi-bin/mainfunction.cgi endpoint.
    Affected if The web interface is accessible from an untrusted network.
  4. Confirm authentication is not bypassed
    The vulnerability requires valid credentials to exploit. Verify whether default credentials are in use or if the authentication system is functioning normally.
    Affected if Valid administrative credentials exist or can be obtained.

A DrayTek Vigor3900, Vigor2960, or Vigor300B router is affected if it runs firmware versions prior to 1.5.1 and has its web management interface exposed with accessible credentials.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.5.1 or later
Fixed in 1.5.1
Interim mitigation

Upgrade affected devices to firmware version 1.5.1 or later. If immediate patching is not possible, restrict network access to the admin web interface (port 443/80) to trusted IPs only.

Recommended fix High confidence

Firmware 1.5.1

  1. Download the firmware version 1.5.1 for your specific model (Vigor3900, Vigor2960, or Vigor300b) from the official DrayTek website www.draytek.com
  2. Access the device web administration interface
  3. Navigate to the System Maintenance or Firmware Upgrade section
  4. Upload the downloaded firmware version 1.5.1
  5. Wait for the firmware upload and reboot to complete
  6. Verify the firmware version has been updated to 1.5.1 in the device status page

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Vigor3900 Firmware Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,440
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-15415 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data