Network Services OrchestratorApplication · Cisco
CVE-2023-20040
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 · uneditedA vulnerability in the NETCONF service of Cisco Network Services Orchestrator (NSO) could allow an authenticated, remote attacker to cause a denial of service (DoS) on an affected system that is running as the root user. To exploit this vulnerability, the attacker must be a member of the admin group. This vulnerability exists because user-supplied input is not properly validated when NETCONF is used to upload packages to an affected device. An attacker could exploit this vulnerability by uploading a specially crafted package file. A successful exploit could allow the attacker to write crafted files to arbitrary locations on the filesystem or delete arbitrary files from the filesystem of an affected device, resulting in a DoS condition. Note: By default, during install, Cisco NSO will be set up to run as the root user unless the --run-as-user option is used.
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 confidenceA path traversal vulnerability in the NETCONF service of Cisco NSO allows authenticated admin users to write crafted files to arbitrary locations or delete arbitrary files on the filesystem by uploading specially crafted package files, due to improper input validation during package upload.
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
Network Services OrchestratorApplication
>= 3.3, < 5.4.7>= 5.5, < 5.5.6>= 5.6, < 5.6.7>= 5.7, < 5.7.4= 5.8CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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 Cisco NSO versionRun 'ncs --version' or check the ncs package version installed on the system. The version is typically located in the NSO installation directory or reported by the 'ncs' command.Affected if The installed version falls within these ranges: >= 3.3 and < 5.4.7, OR >= 5.5 and < 5.5.6, OR >= 5.6 and < 5.6.7, OR >= 5.7 and < 5.7.4, OR equals 5.8.
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Confirm NETCONF service is accessibleVerify that the NETCONF service is enabled and listening. Check with 'ncs_status' command or review the NETCONF listener configuration in the NSO configuration files (typically in ~ncs/yang/.conf or similar).Affected if NETCONF service is enabled and accessible over SSH or HTTP.
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Verify admin user authentication is configuredCheck the NSO authentication configuration for admin-level users. Review the 'ncs.conf' file or use 'ncs_cli -u admin' to see if admin users exist. Look for users with admin privileges in the NSO AAA configuration.Affected if Authenticated admin users exist who can access the NETCONF service and upload packages.
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Check NSO package management capabilityDetermine if the NETCONF package upload feature is available. This is typically accessible via the NETCONF 'upload-package' RPC or through the NSO CLI 'packages' command. Verify admin users have package management permissions.Affected if Admin users have permission to upload NSO packages via NETCONF.
Your environment is affected if Cisco NSO is running a version within the affected ranges AND the NETCONF service is accessible with admin users who can upload packages.
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.
dbcve · scoped5.4.75.5.65.6.7
Apply the Cisco patch for this vulnerability; alternatively, run NSO with the --run-as-user option to run as non-root and limit admin group membership to reduce attack surface.
Upgrade to 5.4.7+, 5.5.6+, 5.6.7+, or 5.7.4+ depending on your version branch (e.g., 5.7.4 or later for the 5.7 branch)
- 1. Identify the currently installed Cisco NSO version using 'ncs --version' or checking the installation directory
- 2. Determine the appropriate upgrade path based on your current version branch (5.4.x, 5.5.x, 5.6.x, or 5.7.x)
- 3. Download the fixed version from Cisco (either 5.4.7+, 5.5.6+, 5.6.7+, or 5.7.4+)
- 4. Review Cisco NSO upgrade documentation and release notes for your target version
- 5. Back up the current NSO configuration and data directories before upgrading
- 6. Stop the NSO service using 'ncs --stop'
- 7. Install the fixed version following Cisco's standard upgrade procedure
- 8. Start the NSO service and verify it is running correctly
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Network Services Orchestrator
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-20040 — 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-2023-20040 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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