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iOSOperating system · Cisco

CVE-2015-6278

HIGH · 7.8 CVSS v2.0 Published 2015-09-28
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
The IPv6 snooping functionality in the first-hop security subsystem in Cisco IOS 12.2, 15.0, 15.1, 15.2, 15.3, 15.4, and 15.5 and IOS XE 3.2SE, 3.3SE, 3.3XO, 3.4SG, 3.5E, and 3.6E before 3.6.3E; 3.7E before 3.7.2E; 3.9S and 3.10S before 3.10.6S; 3.11S before 3.11.4S; 3.12S and 3.13S before 3.13.3S; and 3.14S before 3.14.2S does not properly implement the Control Plane Protection (aka CPPr) feature, which allows remote attackers to cause a denial of service (device reload) via a flood of ND packets, aka Bug ID CSCus19794.

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

This vulnerability exists in Cisco IOS and IOS XE's IPv6 first-hop security (snooping) subsystem, which fails to properly enforce Control Plane Protection (CPPr). Remote attackers can exploit this by sending a flood of IPv6 Neighbor Discovery (ND) packets to the affected device, causing it to reload and resulting in a denial of service.

MitigationUpgrade to a fixed IOS/IOS XE version (3.6.3E, 3.7.2E, 3.10.6S, 3.11.4S, 3.13.3S, or 3.14.2S and later). As an interim measure, implement control-plane policing to rate-limit ND packets reaching the CPU.

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\(50\)sy= 12.2\(50\)sy1= 12.2\(50\)sy2= 12.2\(50\)sy3= 12.2\(50\)sy4= 15.0\(1\)ex= 15.0\(1\)sy= 15.0\(1\)sy1= 15.0\(1\)sy2= 15.0\(1\)sy3= 15.0\(1\)sy4= 15.0\(1\)sy5
Ios XeOperating system
Affected:= 3.2se.0= 3.2se.1= 3.2se.2= 3.2se.3= 3.3se.0= 3.3se.1= 3.3se.2= 3.3se.3= 3.3se.4= 3.3se.5= 3.3xo.0= 3.3xo.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. Identify the IOS/IOS XE version
    Execute 'show version' on the device CLI and locate the version string in the output
    Affected if The version matches one of the affected releases: 12.2(50)sy through 12.2(50)sy4, 15.0(1)ex, 15.0(1)sy through 15.0(1)sy5 for IOS; or 3.2se.0 through 3.2se.3, 3.3se.0 through 3.3se.5, 3.3xo.0, 3.3xo.1 for IOS XE
  2. Verify IPv6 is enabled
    Execute 'show ipv6 interface brief' or 'show running-config | include ipv6'
    Affected if IPv6 is enabled and configured on any interface
  3. Confirm IPv6 snooping feature is active
    Execute 'show ipv6 snooping' or 'show running-config | include snooping'
    Affected if IPv6 snooping (first-hop security) is configured and running on the device
  4. Check Control Plane Protection status
    Execute 'show control-plane' and review the output for CPPr configuration
    Affected if CPPr is not properly enforcing rate-limiting or policing for IPv6 Neighbor Discovery traffic destined to the control plane

The device is affected if it runs an affected IOS/IOS XE version, has IPv6 enabled, and has IPv6 snooping configured without proper CPPr enforcement for ND packets.

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

Upgrade to a fixed IOS/IOS XE version (3.6.3E, 3.7.2E, 3.10.6S, 3.11.4S, 3.13.3S, or 3.14.2S and later). As an interim measure, implement control-plane policing to rate-limit ND packets reaching the CPU.

Fix this in iOS Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,440
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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-2015-6278 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