iOSOperating system · Cisco
CVE-2015-0586
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 Network-Based Application Recognition (NBAR) protocol implementation in Cisco IOS 15.3(100)M and earlier on Cisco 2900 Integrated Services Router (aka Cisco Internet Router) devices allows remote attackers to cause a denial of service (NBAR process hang) via IPv4 packets, aka Bug ID CSCuo73682.
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 confidenceThe NBAR (Network-Based Application Recognition) protocol implementation in Cisco IOS 15.3(100)M and earlier on Cisco 2900 Integrated Services Router devices contains a vulnerability when processing specially crafted IPv4 packets. Remote attackers can send malicious IPv4 packets to trigger a denial of service condition that causes the NBAR process to hang or become unresponsive.
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
<= 15.3\(100\)mCVSS 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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Identify the Cisco device modelLog into the device and run 'show version' or 'show inventory' to confirm the hardware platform. Look for Cisco 2900 Series Integrated Services Router.Affected if The device is not a Cisco 2900 Series ISR (other models may have separate advisories)
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Check the Cisco IOS versionRun 'show version' and locate the IOS version string (for example, 15.3(100)M). Compare it to the affected range: any version 15.3(100)M or earlier.Affected if The IOS version is 15.3(100)M or any earlier 15.x release (the vulnerability exists in versions up to and including 15.3(100)M)
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Verify NBAR is enabledRun 'show nbar protocol-discovery' or 'show ip nbar protocol-discovery' to check if NBAR is actively processing traffic. Also check the running configuration with 'show run | include nbar' to see if NBAR is configured.Affected if NBAR is enabled and configured on the device - the vulnerability only triggers when NBAR is actively processing IPv4 packets
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Confirm IPv4 routing is activeRun 'show ip interface brief' to verify IPv4 interfaces are configured and up. The exploit vector is specially crafted IPv4 packets sent to the device.Affected if The device has IPv4 interfaces configured and is processing IPv4 traffic - this is required for the denial of service condition to be triggered
You are affected if you are running Cisco IOS 15.3(100)M or earlier on a Cisco 2900 ISR with NBAR enabled and IPv4 interfaces active, as the vulnerability requires NBAR to process malicious IPv4 packets.
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 Cisco IOS to a version that addresses this vulnerability (later than 15.3(100)M). If immediate patching is not feasible, consider disabling NBAR if not required for network operations, or implement network segmentation and access controls to limit exposure to untrusted IPv4 traffic.
Fix this in iOS
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-0586 — 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-2015-0586 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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