CVE-2011-1925
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 · uneditednbd-server.c in Network Block Device (nbd-server) 2.9.21 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) by causing a negotiation failure, as demonstrated by specifying a name for a non-existent export.
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 confidenceIn nbd-server 2.9.21, when a client connects and requests an export name that does not exist on the server, the negotiation process fails and the server attempts to dereference a NULL pointer. This occurs because the code does not validate that the export exists before attempting to use it, leading to a crash and denial of service.
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<= 2.9.21CVSS 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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Check if nbd-server is installedRun 'which nbd-server' or check your package manager for the nbd-server packageAffected if nbd-server is not found on the system, so the vulnerability does not apply
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Determine the installed nbd-server versionRun 'nbd-server --version' or use your package manager to query the installed version (e.g., 'dpkg -l nbd-server' or 'rpm -qi nbd-server')Affected if The installed version is 2.9.21 or earlier
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Verify nbd-server configuration exportsExamine the nbd-server configuration file (typically /etc/nbd-server.conf) and list all defined export names in the [exports] sectionAffected if The server has exports configured, but the vulnerability triggers when a client requests a non-existent export name during negotiation
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Confirm the server is running and network-accessibleCheck if nbd-server process is running ('ps aux | grep nbd') and listening on its configured port (default 10809) using 'netstat -tlnp | grep 10809' or 'ss -tlnp | grep 10809'Affected if The server is running and accessible to network clients, which is required for the NULL pointer dereference to occur during client negotiation
You are affected if nbd-server version 2.9.21 or earlier is installed and running with network accessibility, since a client connecting and requesting a non-existent export name will trigger the NULL pointer dereference crash.
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 nbd-server to a version after 2.9.21 that includes proper NULL pointer validation when handling export name lookups during client negotiation, or implement input validation to reject invalid export names before dereferencing pointers.
- Consultation1.0 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-2011-1925 — 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-2011-1925 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
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