dbcve.org
Ios XrOperating system · Cisco

CVE-2011-0943

HIGH · 7.8 CVSS v2.0 Published 2011-05-31
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
Cisco IOS XR 3.8.3, 3.8.4, and 3.9.1 allows remote attackers to cause a denial of service (NetIO process restart or device reload) via a crafted IPv4 packet, aka Bug ID CSCth44147.

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 confidence

A denial of service vulnerability in Cisco IOS XR versions 3.8.3, 3.8.4, and 3.9.1 allows remote attackers to send crafted IPv4 packets that cause the NetIO process to restart or trigger a device reload. The attack is low complexity, requires no authentication, and can be exploited remotely over the network.

MitigationApply the Cisco IOS XR patch for Bug ID CSCth44147 (upgrade to a fixed version) or implement network filtering/ACLs to block malformed IPv4 packets at network edges before they reach affected devices.

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
Affected:= 3.8.3= 3.8.4= 3.9.1

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Determine the Cisco IOS XR version
    Log into the device CLI and run 'show version' or 'admin show version' to display the installed IOS XR software version
    Affected if The displayed version is exactly 3.8.3, 3.8.4, or 3.9.1
  2. Verify IPv4 is enabled on the device
    Run 'show ip interface brief' or review the running configuration for any 'ipv4' address assignments under interface configurations
    Affected if One or more interfaces have IPv4 addresses configured and are active
  3. Confirm NetIO process availability
    Run 'show process netio' or 'admin show process netio' to verify the NetIO process is running and handling packet processing
    Affected if The NetIO process is running and IPv4 traffic is being processed

The device is affected if it runs Cisco IOS XR version 3.8.3, 3.8.4, or 3.9.1 and has IPv4 interfaces configured with the NetIO process active.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco IOS XR patch for Bug ID CSCth44147 (upgrade to a fixed version) or implement network filtering/ACLs to block malformed IPv4 packets at network edges before they reach affected devices.

Fix this in Ios Xr Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
Get help mitigating

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 locally
dbcve dependency scanner

Check whether your project pulls in CVE-2011-0943 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-0943 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data