Nx OsOperating system · Cisco
CVE-2012-4122
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 · uneditedThe CLI parser in Cisco NX-OS allows local users to bypass intended access restrictions, and overwrite or create arbitrary files, via shell output redirection, aka Bug IDs CSCts56672 and CSCts56669.
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 confidenceThis vulnerability in Cisco NX-OS CLI parser allows local authenticated users to bypass intended access restrictions through shell output redirection. Users can overwrite or create arbitrary files on the system by manipulating redirection operators in CLI commands, effectively achieving arbitrary file write access beyond their intended privileges.
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
Nx OsOperating system
all versionsCVSS 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
- Authentication
- Single
- Confidentiality
- None
- Integrity
- Complete
- Availability
- Complete
AV:L/AC:L/Au:S/C:N/I:C/A:C
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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Confirm the device is running Cisco NX-OSRun 'show version' or 'show module' command to identify the operating systemAffected if The device runs any version of Cisco NX-OS (all versions are affected)
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Identify local CLI user accounts with write accessRun 'show user account' or 'show running-config | include username' to enumerate local usersAffected if Any local authenticated user account exists on the NX-OS device, which is the prerequisite for this vulnerability
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Review CLI command history for suspicious redirection operatorsRun 'show history' or check audit logs for commands containing '>' or '>>' redirection to paths outside user home directoriesAffected if Commands using redirection to system directories like /bootflash, /var/log, or /config are present in logs
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Inspect file system for unauthorized modificationsCompare checksums of critical system files in /bootflash and /config against known-good baselines using 'show file' or 'cksum'Affected if System files, configuration files, or scripts have been modified by unexpected users
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Check for unexpected files in privileged locationsList files in /bootflash, /var/log, and /config directories using 'dir /bootflash' or 'ls -la'Affected if Newly created files appear in system directories without documented justification
A Cisco NX-OS device with local authenticated user accounts present is affected, and evidence of unauthorized file writes via CLI redirection confirms active exploitation.
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 dataApply the relevant Cisco NX-OS patch or upgrade to a fixed software version. Until patched, limit local CLI access to trusted personnel only and monitor for suspicious command execution.
Fix this in Nx Os
Scoped from the published advisory
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 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 $4,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-4122 — 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-2012-4122 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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
- No spam, self-promotion, credentials, or personal data