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Download StationApplication · Synology

CVE-2021-34810

HIGH · 8.8 CVSS v3.1 Published 2021-06-18
Fix available
A fix is available. Upgrade to 3.8.16-3566 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
Improper privilege management vulnerability in cgi component in Synology Download Station before 3.8.16-3566 allows remote authenticated users to execute arbitrary code via unspecified vectors.

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 · moderate confidence

Improper privilege management vulnerability in Synology Download Station's CGI component allows authenticated remote users to execute arbitrary code. The vulnerability stems from insufficient authorization checks in the CGI interface, enabling privilege escalation or command injection by authenticated users.

MitigationUpdate Synology Download Station to version 3.8.16-3566 or later. Until patched, limit access to trusted authenticated users only and monitor for suspicious activity.

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
Download StationApplication
Affected:< 3.8.16-3566

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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. Confirm Synology Download Station is installed
    Check the Synology package center or list installed packages. On the NAS, navigate to Package Center or run: cat /var/packages/DownloadStation/package.info
    Affected if Download Station package is not found or not installed - not affected
  2. Identify installed Download Station version
    In Package Center, click on Download Station and view the version information. Alternatively, access the web UI and check About section, or examine /var/packages/DownloadStation/etc on the NAS
    Affected if Version is 3.8.16-3566 or lower, or version cannot be determined (unknown)
  3. Verify CGI interface is enabled
    Check Synology web station settings or examine the Download Station web UI configuration. The CGI component is typically at /webapi/downloadstation/cgi.cgi
    Affected if CGI interface is accessible and enabled in the web server configuration
  4. Confirm web interface is exposed
    Check if Download Station web portal is accessible externally or internally via HTTP/HTTPS. Inspect web station virtual host settings in Synology Control Panel
    Affected if Web interface is reachable over the network (authenticated users can access it)

Affected if Synology Download Station is installed with version lower than 3.8.16-3566 and its CGI-based web interface is accessible to authenticated users.

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 3.8.16-3566 or later
Fixed in 3.8.16-3566
Interim mitigation

Update Synology Download Station to version 3.8.16-3566 or later. Until patched, limit access to trusted authenticated users only and monitor for suspicious activity.

Recommended fix High confidence

3.8.16-3566 or later

  1. Log into your Synology NAS and open Package Center
  2. Locate Synology Download Station in the list of installed packages
  3. Check the current version to confirm it is below 3.8.16-3566
  4. Back up any critical downloads or Download Station configuration if desired
  5. Click 'Update' to install the latest available version of Download Station
  6. Verify the installed version is 3.8.16-3566 or later after the update completes
  7. Test that Download Station functionality works normally
Caveat Standard Synology package update precautions apply; minor version upgrades typically preserve settings

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

Fix this in Download Station Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2021-34810 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