iOSOperating system · Cisco
CVE-2012-0338
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 IOS 12.2 through 12.4 and 15.0 does not recognize the vrf-also keyword during enforcement of access-class commands, which allows remote attackers to establish SSH connections from arbitrary source IP addresses via a standard SSH client, aka Bug ID CSCsv86113.
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 Cisco IOS 12.2-12.4 and 15.0, the vrf-also keyword is not recognized during access-class command enforcement. This causes SSH access-list restrictions to fail, allowing remote attackers to establish SSH connections from arbitrary source IP addresses instead of being limited to the configured permit list.
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
iOSOperating system
= 12.2= 12.3= 12.4= 15.0CVSS 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
- Partial
- Availability
- None
AV:N/AC:L/Au:N/C:N/I:P/A:N
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 IOS versionRun 'show version' and locate the IOS release number in the outputAffected if The version begins with 12.2, 12.3, 12.4, or 15.0 (any subversion within these main releases)
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Confirm SSH is enabledRun 'show ip ssh' or check configuration for 'ip ssh version' under global configAffected if SSH is enabled and configured on the device
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Examine vty line access-class configurationRun 'show running-config | include vty' or 'show line vty 0 4' to review the vty line configuration, then check for 'access-class' statementsAffected if An access-class is applied to vty lines for SSH (typically via 'access-class <name> in')
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Identify if vrf-also keyword is used with access-classRun 'show running-config | include access-class' and review the full vty configuration for the 'vrf-also' keyword appended to the access-class statement (e.g., 'access-class <name> in vrf-also')Affected if The configuration includes 'vrf-also' on the access-class statement applied to vty lines
A device is affected if it runs IOS 12.2, 12.3, 12.4, or 15.0, has SSH enabled, uses access-class on vty lines, and includes the vrf-also keyword in the access-class configuration.
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 to a patched Cisco IOS version that addresses Bug ID CSCsv86113, or implement alternative access controls (such as interface ACLs) to restrict SSH source IPs until patching is feasible.
Fix this in iOS
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 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 $2,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-0338 — 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-2012-0338 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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