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iOSOperating system · Cisco

CVE-2016-6382

HIGH · 7.5 CVSS v3.0 Published 2016-10-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
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
Cisco IOS 15.2 through 15.6 and IOS XE 3.6 through 3.17 and 16.1 allow remote attackers to cause a denial of service (device restart) via a malformed IPv6 Protocol Independent Multicast (PIM) register packet, aka Bug ID CSCuy16399.

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 vulnerability in Cisco IOS and IOS XE allows remote attackers to cause denial of service by sending malformed IPv6 Protocol Independent Multicast (PIM) register packets. The malformed packet triggers a device restart, as the affected software versions (IOS 15.2-15.6 and IOS XE 3.6-3.17/16.1) fail to properly validate the IPv6 PIM packet structure before processing.

MitigationApply the relevant Cisco security patch for this vulnerability. If immediate patching is not feasible, consider filtering or blocking untrusted IPv6 PIM traffic at network boundaries until the update can be deployed.

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:= 15.2\(1\)sy= 15.2\(1\)sy0a= 15.2\(1\)sy1= 15.2\(1\)sy1a= 15.2\(2\)e= 15.2\(2\)e1= 15.2\(2\)e2= 15.2\(2\)e4= 15.2\(2\)ea1= 15.2\(2\)ea2= 15.2\(2\)ea3= 15.2\(2\)eb
Ios XeOperating system
Affected:= 3.6.0e= 3.6.1e= 3.6.2ae= 3.6.2e= 3.6.3e= 3.6.4e= 3.7.0e= 3.7.1e= 3.7.2e= 3.7.3e= 3.8.0e= 3.8.1e

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
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 checks

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

  1. Identify the Cisco IOS or IOS XE version
    Execute 'show version' on the device CLI and locate the version string in the output (e.g., 'Version 15.2(2)E4' or 'Version 16.1(1)T').
    Affected if The version matches or falls within the affected ranges: Cisco iOS 15.2(1)sy through 15.2(2)eb, or Cisco IOS XE 3.6.0e through 3.8.1e.
  2. Confirm IPv6 is enabled on the device
    Execute 'show ipv6 interface brief' or 'show running-config | include ipv6' to see if IPv6 is configured.
    Affected if IPv6 is enabled and the device is running a vulnerable IOS/IOS XE version.
  3. Check if IPv6 PIM is configured
    Execute 'show ipv6 pim interface' or examine the running configuration for 'ipv6 pim' commands.
    Affected if IPv6 Protocol Independent Multicast (PIM) is enabled on any interface and the device runs a vulnerable version.
  4. Verify IPv6 PIM register processing
    Execute 'show ipv6 pim neighbor' or 'show ipv6 pim interface' to confirm active PIM adjacencies that could receive register packets.
    Affected if The device has IPv6 PIM neighbors or interfaces with PIM enabled, placing it at risk when receiving malformed IPv6 PIM register packets.

The device is affected if it runs a vulnerable Cisco IOS 15.2-15.6 or IOS XE 3.6-3.18/16.1 version AND has IPv6 PIM enabled, allowing malformed IPv6 PIM register packets to trigger a restart.

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 the relevant Cisco security patch for this vulnerability. If immediate patching is not feasible, consider filtering or blocking untrusted IPv6 PIM traffic at network boundaries until the update can be deployed.

Fix this in iOS Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2016-6382 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