Ios XeOperating system · Cisco
CVE-2017-3820
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 · uneditedA vulnerability in Simple Network Management Protocol (SNMP) functions of Cisco ASR 1000 Series Aggregation Services Routers running Cisco IOS XE Software Release 3.13.6S, 3.16.2S, or 3.17.1S could allow an authenticated, remote attacker to cause high CPU usage on an affected device, resulting in a denial of service (DoS) condition. More Information: CSCux68796. Known Affected Releases: 15.5(3)S2.1 15.6(1)S1.1. Known Fixed Releases: 15.4(3)S6.1 15.4(3)S6.2 15.5(3)S2.2 15.5(3)S3 15.6(0.22)S0.23 15.6(1)S2 16.2(0.295) 16.3(0.94) 15.5.3S3.
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 the SNMP implementation of Cisco ASR 1000 Series routers running specific IOS XE releases (3.13.6S, 3.16.2S, 3.17.1S and related 15.x versions) allows an authenticated remote attacker to send specially crafted SNMP packets that trigger excessive CPU consumption, causing denial of service.
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
= 3.13.6s= 3.16.2s= 3.17.1sCVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:L/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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Confirm Cisco ASR 1000 Series router modelUse the 'show version' command or check hardware inventory to verify the device is a Cisco ASR 1000 Series router running IOS XEAffected if Device is a Cisco ASR 1000 Series router running IOS XE software
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Identify the IOS XE versionExecute 'show version' and locate the IOS XE release string (for example, Version 3.13.6S, Version 3.16.2S, or Version 3.17.1S)Affected if The installed IOS XE version matches 3.13.6S, 3.16.2S, 3.17.1S, or related 15.x versions in the same train
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Verify SNMP is enabledRun 'show snmp' or 'show running-config | include snmp' to check if SNMP is configured and active on the deviceAffected if SNMP is enabled with any community string configuration (even if changed from default)
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Check SNMP community string configurationRun 'show snmp community' to view configured SNMP community stringsAffected if Read-write or read-only SNMP community strings are configured, allowing authenticated SNMP access
The environment is affected if the device is a Cisco ASR 1000 Series router running IOS XE versions 3.13.6S, 3.16.2S, or 3.17.1S (or related 15.x versions in those trains) and SNMP is enabled with configured community strings.
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 XE Software to a fixed release (15.4(3)S6.1+, 15.5(3)S2.2+, 15.6(1)S2+, 16.2+, or 16.3+) per the Cisco advisory. If upgrade is not immediately feasible, restrict SNMP access to trusted management networks or disable SNMP if not required.
Fix this in Ios Xe
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 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 $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-3820 — 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-2017-3820 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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