Ios XrOperating system · Cisco
CVE-2011-3295
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 NETIO and IPV4_IO processes in Cisco IOS XR 3.8 through 4.1, as used in Cisco Carrier Routing System and other products, allow remote attackers to cause a denial of service (CPU consumption) via crafted network traffic, aka Bug ID CSCti59888.
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 · moderate confidenceA denial of service vulnerability in Cisco IOS XR versions 3.8 through 4.1 allows remote attackers to trigger excessive CPU consumption in the NETIO and IPV4_IO processes by sending specially crafted network traffic, causing the system to become unresponsive to legitimate traffic.
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
Ios XrOperating system
= 3.8.0= 3.8.1= 3.8.2= 3.8.3= 3.8.4= 3.9.0= 3.9.1= 3.9.2= 4.0.0= 4.0.1= 4.0.2= 4.0.3CVSS 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
- Complete
AV:N/AC:L/Au:N/C:N/I:N/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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Determine Cisco IOS XR versionExecute 'show version' or 'admin show version' command on the IOS XR device to display the running software versionAffected if The displayed version matches 3.8.0, 3.8.1, 3.8.2, 3.8.3, 3.8.4, 3.9.0, 3.9.1, 3.9.2, 4.0.0, 4.0.1, 4.0.2, or 4.0.3
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Confirm NETIO process is runningExecute 'show process netio' or 'show process | include NETIO' to display NETIO process status and CPU utilizationAffected if The NETIO process is active and showing unexpectedly high CPU usage, especially when under suspicious incoming network traffic
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Confirm IPV4_IO process is runningExecute 'show process ipv4_io' or 'show process | include IPV4_IO' to display IPV4_IO process status and CPU utilizationAffected if The IPV4_IO process is active and showing high CPU consumption beyond normal baseline levels
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Check for system unresponsiveness indicatorsObserve console output, monitor response to SSH/Telnet connections, and check 'show tech-support' or 'show log' for error messages related to process congestionAffected if The system exhibits sluggishness, delayed responses, or log entries indicating NETIO or IPV4_IO is consuming excessive CPU cycles when processing network traffic
A system is affected if it runs Cisco IOS XR version 3.8.0 through 4.0.3 and exhibits high CPU usage in the NETIO or IPV4_IO processes under normal network traffic conditions.
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 Cisco IOS XR patch or upgrade to a version beyond 4.1 that addresses Bug ID CSCti59888. If immediate patching is not possible, consider network segmentation or ACLs to limit exposure to untrusted network segments.
Fix this in Ios Xr
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 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 $6,656.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-3295 — 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-2011-3295 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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