dbcve.org
Serv UApplication · Solarwinds

CVE-2021-35250

HIGH · 7.5 CVSS v3.1 Published 2022-04-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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
A researcher reported a Directory Transversal Vulnerability in Serv-U 15.3. This may allow access to files relating to the Serv-U installation and server files. This issue has been resolved in Serv-U 15.3 Hotfix 1.

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

A directory traversal vulnerability in Serv-U FTP server version 15.3 allows attackers to use path manipulation techniques to access files outside the intended directory scope, potentially exposing Serv-U installation files and other server files.

MitigationUpgrade Serv-U to version 15.3 Hotfix 1 or later to apply the vendor patch. If immediate patching is not feasible, review and restrict file access controls and monitor for anomalous file access patterns.

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
Serv UApplication
Affected:= 15.3

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
None
Availability
None

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

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 Serv-U installation exists
    Check for Serv-U installation directory, typically at C:\Program Files\SolarWinds\Serv-U on Windows or /usr/local/serv-u on Linux. Also check for Serv-U processes running via task manager (Windows) or ps command (Linux).
    Affected if Serv-U is installed on the system
  2. Identify installed Serv-U version
    Locate the Serv-U executable or check version information. On Windows, right-click Serv-U.exe and select Properties > Details to view File Version. On Linux, run 'Serv-U -v' or check the version file in the installation directory.
    Affected if The installed version is exactly 15.3 (not 15.3 Hotfix 1 or later)
  3. Verify FTP service is accessible
    Check if the Serv-U FTP service is running and listening on port 21 (or configured FTP port). Use netstat -an | findstr :21 on Windows or netstat -tuln | grep :21 on Linux to confirm the service is bound to a listening port.
    Affected if The Serv-U FTP service is running and accepting connections
  4. Check for file access patterns in logs
    Review Serv-U logs in the logs subdirectory for any entries containing ../ or path traversal sequences. Logs may show attempted traversal patterns accessing parent directories outside the configured root directory.
    Affected if Log entries show path traversal sequences or unauthorized directory access attempts

The system is affected only if Serv-U is installed, the exact version is 15.3 (not patched with Hotfix 1 or later), and the FTP service is running and accessible.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Serv-U to version 15.3 Hotfix 1 or later to apply the vendor patch. If immediate patching is not feasible, review and restrict file access controls and monitor for anomalous file access patterns.

Recommended fix High confidence

Serv-U 15.3 Hotfix 1

  1. Download Serv-U 15.3 Hotfix 1 from the SolarWinds support portal (support.solarwinds.com)
  2. Apply the hotfix to your Serv-U installation following the documentation provided with the hotfix
  3. Restart the Serv-U service after applying the hotfix
  4. Verify the patch was applied successfully by checking the Serv-U version or build number

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

Fix this in Serv U Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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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-2021-35250 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