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iOSOperating system · Cisco

CVE-2015-6279

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 allows remote attackers to cause a denial of service (device reload) via a malformed ND packet with the Cryptographically Generated Address (CGA) option, aka Bug ID CSCuo04400.

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

A denial-of-service vulnerability exists in Cisco IOS and IOS XE's IPv6 first-hop security (snooping) subsystem. Attackers can trigger a device reload by sending a malformed Neighbor Discovery (ND) packet containing a specifically crafted Cryptographically Generated Address (CGA) option. The vulnerability affects multiple IOS 12.2/15.x and IOS XE 3.2-3.14 branches.

MitigationUpgrade Cisco IOS or IOS XE to a patched version (IOS XE 3.6.3E, 3.7.2E, 3.10.6S, 3.11.4S, 3.13.3S, 3.14.2S or later). If upgrading is not immediately feasible, consider disabling IPv6 snooping or implementing ACL filtering for malformed ND packets at network edges.

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 or IOS XE version
    Run 'show version' on the device CLI and locate the version string (e.g., 15.0(1)SY, 3.2SE)
    Affected if The displayed version matches one of the affected versions listed in the CVE (12.2(50)sy through 12.2(50)sy4, 15.0(1)ex through 15.0(1)sy5 for IOS; 3.2SE.0 through 3.3XO.1 for IOS XE)
  2. Verify IPv6 snooping is enabled
    Run 'show running-config | include ipv6 snooping' or 'show ipv6 snooping' to see if the IPv6 snooping feature is configured
    Affected if IPv6 snooping is actively enabled in the configuration or shows as active in the feature status

The device is affected if it runs a matching vulnerable IOS/IOS XE version AND has IPv6 snooping feature enabled, as the flaw only triggers through this specific subsystem.

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 Cisco IOS or IOS XE to a patched version (IOS XE 3.6.3E, 3.7.2E, 3.10.6S, 3.11.4S, 3.13.3S, 3.14.2S or later). If upgrading is not immediately feasible, consider disabling IPv6 snooping or implementing ACL filtering for malformed ND packets at network edges.

Fix this in iOS Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2015-6279 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