12000 RouterHardware / appliance · Cisco
CVE-2001-0866
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 12000 with IOS 12.0 and lines card based on Engine 2 does not properly handle an outbound ACL when an input ACL is not configured on all the interfaces of a multi port line card, which could allow remote attackers to bypass the intended access controls.
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 12000 series routers running IOS 12.0 with Engine 2-based line cards fail to properly enforce outbound access control lists when input ACLs are not configured on all interfaces of a multi-port line card. This configuration mismatch allows traffic to bypass outbound ACL restrictions, potentially permitting unauthorized network access.
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
12000 RouterHardware / appliance
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
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:P/A:P
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 the router modelUse the command 'show version' or 'show hardware' to confirm the device is a Cisco 12000 series routerAffected if Router model is Cisco 12000 series
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Check the IOS versionUse the command 'show version' to display the installed IOS versionAffected if IOS version begins with 12.0
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Identify Engine 2-based line cardsUse the command 'show controllers' to list all line cards and identify their engine typesAffected if Any line card is identified as Engine 2-based
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Verify ACL configuration on interfacesUse the command 'show ip interface' on each interface of the Engine 2 line cards to check for input ACLs (Inbound access list)Affected if At least one interface on an Engine 2 line card has NO input ACL configured while outbound ACLs exist on that or other interfaces
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Test for ACL bypass behaviorSend test traffic that should be blocked by an outbound ACL on an interface without an input ACL, and verify if the traffic is unexpectedly permittedAffected if Traffic passes despite outbound ACL deny rules when no input ACL is on that interface
The environment is affected if running a Cisco 12000 router on IOS 12.0 with Engine 2 line cards that have outbound ACLs configured but lack input ACLs on all interfaces, allowing traffic to bypass the outbound restrictions.
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 dataEnsure input ACLs are configured on ALL interfaces of affected line cards, or migrate to newer IOS versions and hardware platforms that properly handle mixed ACL configurations.
Fix this in 12000 Router
Scoped from the published advisory
- Consultation8.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $10,240.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2001-0866 — 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-2001-0866 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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