12000 RouterHardware / appliance · Cisco
CVE-2001-0863
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 line cards based on Engine 2 does not handle the "fragment" keyword in a compiled ACL (Turbo ACL) for packets that are sent to the router, which allows remote attackers to cause a denial of service via a flood of fragments.
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 confidenceThe Cisco 12000 series routers running IOS 12.0 with Engine 2-based line cards fail to properly handle the 'fragment' keyword when used in compiled ACLs (Turbo ACL feature). When fragmented packets are sent directly to the router (as opposed to passing through it), the router cannot process them correctly, leading to a denial of service condition.
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
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/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 router modelRun 'show version' or 'show hardware' to confirm the device is a Cisco 12000 series routerAffected if The device is a Cisco 12000 series router - continue checking; otherwise, not affected
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Check IOS versionRun 'show version' and look for IOS version 12.0 (any subversion)Affected if IOS version starts with 12.0 - continue checking; otherwise, likely not affected by this specific CVE
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Identify line card engine typeRun 'show controllers' or 'show diag' to identify line card types; look for Engine 2-based line cards in the outputAffected if Engine 2-based line cards are present - continue checking; otherwise, may not be affected
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Check for Turbo ACLs with fragment keywordRun 'show ip access-list' and look for ACL entries containing the 'fragment' keyword; then check if Turbo ACL compilation is enabled via 'show ip access-list compilation' or similar commandAffected if Compiled ACLs (Turbo ACL) using the 'fragment' keyword are configured - router is potentially vulnerable
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Verify direct fragment traffic exposureDetermine if the router's interface IPs are directly reachable from untrusted networks; check if fragmented packets could be sent directly to the router (not just through it)Affected if Router interfaces are directly exposed to external traffic that could include fragments - risk of DoS is present
A Cisco 12000 running IOS 12.0 with Engine 2 line cards and configured Turbo ACLs using the 'fragment' keyword is affected when it can receive fragmented packets directly.
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 IOS to a version that addresses this vulnerability; alternatively, avoid using the 'fragment' keyword in compiled ACLs on affected line cards or implement rate-limiting for fragments at the network perimeter.
Fix this in 12000 Router
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2001-0863 — 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-2001-0863 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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