Nx OsOperating system · Cisco
CVE-2012-4121
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 · uneditedCisco NX-OS allows local users to gain privileges, and read or modify arbitrary files, via the sed (1) r and (2) w commands, aka Bug IDs CSCts56559, CSCts56565, CSCts56570, and CSCts56574.
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 confidenceCisco NX-OS contains a local privilege escalation vulnerability via the sed utility. Local authenticated users can use sed's 'r' command to read arbitrary files and 'w' command to write arbitrary files on the system, potentially allowing privilege escalation to higher privilege levels.
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
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:L/AC:L/Au:S/C:C/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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Identify NX-OS versionRun 'show version' or 'show version | include NX-OS' from the CLI to obtain the installed NX-OS versionAffected if Any version of Cisco NX-OS is running since all versions are affected by this vulnerability
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Verify local shell access existsConfirm whether local authenticated users have access to the Bash shell or theNX-OS guest shell. Check if users can execute commands via 'run bash' or access the guest shellAffected if Local authenticated users have shell access to the system, as the vulnerability requires local command execution
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Confirm sed utility is accessibleFrom the local shell, verify sed is available by running 'which sed' or attempting to execute 'sed --version'Affected if The sed utility is accessible to the local user, which is required to exploit the 'r' (read) and 'w' (write) command vulnerabilities
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Check user privilege levelRun 'show privilege' or 'show user' from the NX-OS CLI to determine the current user's privilege levelAffected if The user is at any privilege level below administrative/root, as privilege escalation would allow them to elevate from their current level
The environment is affected if local authenticated users have shell access to any version of Cisco NX-OS where the sed utility is available for use.
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 software update (CSCts56559, CSCts56565, CSCts56570, or CSCts56574) that addresses this vulnerability. Until patched, limit local shell access to trusted users only.
Fix this in Nx Os
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,880.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-4121 — 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-2012-4121 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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