Ios XeOperating system · Cisco
CVE-2016-6378
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 IOS XE 3.1 through 3.17 and 16.1 through 16.2 allows remote attackers to cause a denial of service (device reload) via crafted ICMP packets that require NAT, aka Bug ID CSCuw85853.
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 confidenceA vulnerability in Cisco IOS XE allows remote attackers to cause denial of service by sending crafted ICMP packets that traverse NAT. The specially crafted packets trigger a device reload, effectively crashing the affected device.
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 XeOperating system
= 3.1.3s= 3.1.4as= 3.1.4s= 3.2.1s= 3.2.2s= 3.3.0s= 3.3.1s= 3.3.2s= 3.4.0s= 3.4.1s= 3.4.2s= 3.4.3sCVSS 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 IOS XE versionRun the command 'show version' on the device CLI and locate the IOS XE version string in the outputAffected if The displayed version matches one of these: 3.1.3s, 3.1.4as, 3.1.4s, 3.2.1s, 3.2.2s, 3.3.0s, 3.3.1s, 3.3.2s, 3.4.0s, 3.4.1s, 3.4.2s, or 3.4.3s
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Determine if NAT is configuredRun 'show running-config | include ip nat' or 'show ip nat translations' to inspect NAT configuration and active translationsAffected if Any NAT configuration appears in the output, indicating NAT is enabled on the device
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Verify the device is reachable via NAT-enabled interfacesReview the network topology and check interface configurations with 'show ip interface brief' to identify interfaces participating in NATAffected if The device has interfaces configured for NAT translation and those interfaces are externally accessible to untrusted networks
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Check for recent unexpected reloadsRun 'show version' to review the system uptime and 'show logging' to search for crash traces or reload reasons around the time of incidentsAffected if The device has reloaded unexpectedly with no clear administrative cause, especially after external network activity
You are affected if your Cisco IOS XE version is one of the listed versions AND NAT is enabled on accessible interfaces, as the vulnerability requires crafted ICMP packets to traverse a NAT boundary to trigger the device reload.
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 to a patched Cisco IOS XE version beyond 3.17 or 16.2. As an interim compensating control, implement ICMP traffic filtering or ACLs on upstream devices to block suspicious ICMP packets.
Fix this in Ios Xe
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 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 $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-6378 — 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-2016-6378 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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