ConfdApplication · Cisco
CVE-2021-1572
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 ConfD could allow an authenticated, local attacker to execute arbitrary commands at the level of the account under which ConfD is running, which is commonly root. To exploit this vulnerability, an attacker must have a valid account on an affected device. The vulnerability exists because the affected software incorrectly runs the SFTP user service at the privilege level of the account that was running when the ConfD built-in Secure Shell (SSH) server for CLI was enabled. If the ConfD built-in SSH server was not enabled, the device is not affected by this vulnerability. An attacker with low-level privileges could exploit this vulnerability by authenticating to an affected device and issuing a series of commands at the SFTP interface. A successful exploit could allow the attacker to elevate privileges to the level of the account under which ConfD is running, which is commonly root. Note: Any user who can authenticate to the built-in SSH server may exploit this vulnerability. By default, all ConfD users have this access if the server is enabled. Software updates that address this vulnerability have been released.
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 ConfD, the SFTP user service incorrectly runs at the privilege level of the account that was active when the ConfD built-in SSH server was enabled, typically root. An authenticated user with valid credentials can exploit this by issuing SFTP commands to execute arbitrary commands with elevated privileges, achieving privilege escalation from a low-level user account to root.
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
ConfdApplication
>= 7.4, <= 7.4.3>= 7.5, <= 7.5.2
Network Services OrchestratorApplication
>= 5.4, <= 5.4.3.1>= 5.5, <= 5.5.2.2CVSS 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
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/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 ConfD or NSO installation and versionRun 'confd --version' or check for confd daemon/process. For NSO, check 'ncs --version'. Compare against affected ranges: ConfD 7.4-7.4.3 or 7.5-7.5.2; NSO 5.4-5.4.3.1 or 5.5-5.5.2.2Affected if Installed version falls within the affected version ranges
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Verify if built-in SSH server is enabledCheck ConfD configuration file (confd.conf) for the <ssh> element under <daemon> or <sshServer>. Alternatively, query ConfD via 'confd_cli -u admin' and run 'show system ssh server' if accessibleAffected if The built-in SSH server is enabled in the configuration
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Confirm SFTP subsystem is configuredSearch confd.conf for <sftp> element or <sftp-server> under the SSH server section. Also check /etc/ssh/sshd_config if external SSH is used with ConfDAffected if SFTP subsystem is configured and available to users
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Identify the user context for the SSH/SFTP serviceReview the ConfD startup script or init/systemd configuration. Check which user account is used to start the ConfD daemon. Look for 'confd' or 'root' user in process listing: 'ps aux | grep confd'Affected if ConfD runs as root or the same elevated user that was active when SSH was enabled
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Check for existing low-privilege SFTP usersQuery ConfD user database via CLI 'show users' or check /etc/passwd for ConfD-managed users. Verify if any users have SFTP access but are not rootAffected if Low-privilege users exist with SFTP access to the system
If ConfD or NSO version is in the affected range AND the built-in SSH server with SFTP is enabled AND the service runs as root, then the environment is vulnerable to privilege escalation via SFTP commands.
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 dataDisable the ConfD built-in SSH server if not required, or apply vendor software updates. If the built-in SSH server is needed, ensure SFTP runs with least-privilege by reconfiguring the service account.
Fix this in Confd
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 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 $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1572 — 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-2021-1572 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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- Version or environment caveats, and links to real fixes
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