CVE-2009-4011
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 · unediteddtc-xen 0.5.x before 0.5.4 suffers from a race condition where an attacker could potentially get a bash access as xenXX user on the dom0, and then access a potentially reuse an already opened VPS console.
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 confidenceA race condition in dtc-xen versions 0.5.x before 0.5.4 allows an attacker to potentially gain bash access as the xenXX user on the dom0 hypervisor, and to reuse an already opened VPS console session.
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>= 0.5.0, < 0.5.4CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/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 checksWork through these to decide whether this CVE applies to you.
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Identify installed dtc-xen versionRun 'dpkg -l dtc-xen' or 'rpm -qi dtc-xen' to see the installed package version, or check the version file in the dtc-xen installation directory if availableAffected if The version displayed is 0.5.0, 0.5.1, 0.5.2, or 0.5.3 (any version from 0.5.0 up to but not including 0.5.4)
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Confirm the dtc-xen package is installedCheck for the presence of dtc-xen packages using your system package manager (dpkg -l | grep dtc-xen or rpm -qa | grep dtc-xen)Affected if The package is installed and the version falls within the 0.5.0 to 0.5.3 range
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Verify console management interface is accessibleCheck if the dtc-xen web interface or command-line console tool is accessible and operational on the systemAffected if The console management features are enabled and in use, and dtc-xen version is vulnerable (0.5.0-0.5.3)
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Check for xenXX user accountsExamine /etc/passwd or similar user database for the presence of xenXX user accounts created by dtc-xen for VPS console accessAffected if xenXX users exist on the system and the dtc-xen version is within the affected range (the race condition could allow unauthorized access to these console sessions)
A system is affected if dtc-xen version 0.5.0, 0.5.1, 0.5.2, or 0.5.3 is installed and the console management features are in use, as the race condition could allow an attacker to gain bash access as the xenXX user or hijack an existing VPS console session.
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 data0.5.4
Upgrade to dtc-xen 0.5.4 or later to address the race condition. If immediate patching is not possible, limit access to the Xen management interface and monitor for unauthorized console access attempts.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-4011 — 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-2009-4011 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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