CVE-2009-3655
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 · uneditedRhino Software Serv-U 7.0.0.1 through 8.2.0.3 allows remote attackers to cause a denial of service (server crash) via unspecified vectors related to the "SITE SET TRANSFERPROGRESS ON" FTP command.
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 confidenceRhino Software Serv-U FTP server versions 7.0.0.1 through 8.2.0.3 contains a denial of service vulnerability where the 'SITE SET TRANSFERPROGRESS ON' FTP command can be exploited by remote attackers to crash the server. The attack vector is network-based via the FTP protocol.
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= 7.0.0.1= 7.0.0.2= 7.0.0.3= 7.0.0.4= 7.1.0.0= 7.1.0.1= 7.1.0.2= 7.2.0.0= 7.2.0.1= 7.3.0.0= 7.3.0.1= 7.3.0.2CVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Serv-U versionCheck the Serv-U server version through the admin console, or use the FTP server bannergrab with a command like `ftp <server>` and look for the version string in the welcome message, or check the Windows service properties if running on Windows.Affected if The installed version matches any of: 7.0.0.1, 7.0.0.2, 7.0.0.3, 7.0.0.4, 7.1.0.0, 7.1.0.1, 7.1.0.2, 7.2.0.0, 7.2.0.1, 7.3.0.0, 7.3.0.1, 7.3.0.2, or any version in the 7.x or 8.x branch up to and including 8.2.0.3.
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Confirm FTP service is network accessibleVerify that the Serv-U FTP port (default port 21) is open and reachable from network locations using a port scanner or by attempting an FTP connection from an external host.Affected if The FTP service is exposed to untrusted network segments or the internet.
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Test for vulnerable SITE SET TRANSFERPROGRESS commandConnect to the FTP server and issue the command `SITE SET TRANSFERPROGRESS ON`. If the server accepts this command without error, the vulnerable code path is present.Affected if The server accepts the SITE SET TRANSFERPROGRESS command and does not reject it or report it as an unknown command.
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Check if server has been crashingReview Serv-U server logs and Windows event logs for crash events or unexpected service restarts around the time of suspicious FTP activity.Affected if There are unexplained server crashes or service restarts correlating with FTP sessions using the SITE SET TRANSFERPROGRESS command.
You are affected if your Serv-U version is 7.0.0.1 through 8.2.0.3, the FTP service is network-accessible, and the server accepts the SITE SET TRANSFERPROGRESS command.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataUpgrade Serv-U to a version beyond 8.2.0.3 where the vulnerability is patched, or if immediate upgrade is not feasible, consider network-level access controls to limit FTP command exposure to trusted sources.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-3655 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2009-3655 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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