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iOSOperating system · Cisco

CVE-2017-3861

HIGH · 8.6 CVSS v3.0 Published 2017-04-20
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
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
Multiple vulnerabilities in the EnergyWise module of Cisco IOS (12.2 and 15.0 through 15.6) and Cisco IOS XE (3.2 through 3.18) could allow an unauthenticated, remote attacker to cause a buffer overflow condition or a reload of an affected device, leading to a denial of service (DoS) condition. These vulnerabilities are due to improper parsing of crafted EnergyWise packets destined to an affected device. An attacker could exploit these vulnerabilities by sending crafted EnergyWise packets to be processed by an affected device. An exploit could allow the attacker to cause a buffer overflow condition or a reload of the affected device, leading to a DoS condition. Cisco IOS Software and Cisco IOS XE Software support EnergyWise for IPv4 communication. Only IPv4 packets destined to a device configured as an EnergyWise domain member can trigger these vulnerabilities. IPv6 packets cannot be used to trigger these vulnerabilities. Cisco Bug ID CSCut47751.

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

Buffer overflow and denial of service vulnerabilities in Cisco IOS (12.2, 15.0-15.6) and IOS XE (3.2-3.18) EnergyWise module allow unauthenticated remote attackers to cause device reload via crafted IPv4 EnergyWise packets. Only affects devices configured as EnergyWise domain members; IPv6 packets cannot trigger these vulnerabilities.

MitigationApply Cisco security updates for EnergyWise vulnerabilities. If patches unavailable, consider disabling EnergyWise on unneeded devices or implementing network access controls to restrict EnergyWise traffic to trusted sources.

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
Affected:= 12.2\(33\)sxi4= 12.2\(33\)sxi4a= 12.2\(33\)sxi5= 12.2\(33\)sxi6= 12.2\(33\)sxi7= 12.2\(33\)sxi8= 12.2\(33\)sxi8a= 12.2\(33\)sxi9= 12.2\(33\)sxi10= 12.2\(33\)sxi11= 12.2\(33\)sxi12= 12.2\(33\)sxi13
Ios XeOperating system
Affected:= 3.2.1sg= 3.2.8sg= 3.3.1sg= 3.3.1sq= 3.4.1sg= 3.4.2sg= 3.4.3sg= 3.4.6sg= 3.4.8sg= 3.5.1e= 3.5.3e= 3.6.0e

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
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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 checks

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

  1. Determine if EnergyWise is enabled
    Run 'show energywise' or 'show energywise summary' in privileged EXEC mode to see if EnergyWise is configured and active on the device
    Affected if EnergyWise is not enabled or not configured - the device is not affected when EnergyWise is completely disabled
  2. Check the IOS or IOS XE version
    Run 'show version' and locate the firmware version string. Compare it against the affected version ranges: IOS 12.2(33)sxi4 through 12.2(33)sxi13, or IOS XE 3.2.1SG through 3.6.0E
    Affected if The installed version matches one of the listed affected versions AND EnergyWise is enabled
  3. Confirm EnergyWise domain membership
    Run 'show energywise domain' to verify the device is configured as a member of an EnergyWise domain
    Affected if The device is NOT a member of any EnergyWise domain - the vulnerability cannot be triggered
  4. Verify IPv4 EnergyWise is configured
    Run 'show energywise interface' and check the EnergyWise configuration on interfaces. Determine if IPv4 (not IPv6) is being used for EnergyWise communications
    Affected if Only IPv6 EnergyWise is in use - the advisory states IPv6 packets cannot trigger these vulnerabilities

The device is affected if it runs a vulnerable IOS or IOS XE version, has EnergyWise enabled, is a member of an EnergyWise domain, and uses IPv4 for EnergyWise communications.

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 Cisco security updates for EnergyWise vulnerabilities. If patches unavailable, consider disabling EnergyWise on unneeded devices or implementing network access controls to restrict EnergyWise traffic to trusted sources.

Fix this in iOS Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,080
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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-2017-3861 in production — separate from our analysis above.

No notes yet

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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