TeredoApplication · Microsoft

CVE-2006-6264

HIGH · 7.5 CVSS v2.0 Published 2006-12-04
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
Teredo creates trusted peer entries for arbitrary incoming source Teredo addresses, even if the low 32 bits represent an intranet address, which might allow remote attackers to send IPv4 traffic to intranet hosts that use non-RFC1918 addresses, bypassing IPv4 ingress filtering.

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

Teredo (IPv6 tunneling protocol) creates trusted peer entries for arbitrary incoming source Teredo addresses without validating whether the low 32 bits represent private/non-RFC1918 intranet addresses. This allows remote attackers to tunnel IPv4 traffic through Teredo to internal hosts using non-RFC1918 addresses (e.g., public IPs that are actually internal), bypassing IPv4 ingress filtering controls.

MitigationImplement validation of the low 32 bits of incoming Teredo addresses to reject or mark untrusted any that map to RFC1918 private address space (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) or other non-routable addresses before creating trusted peer entries.

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
TeredoApplication
Affected:all versions

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
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:L/Au:N/C:P/I:P/A:P

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 Teredo service is running
    Run 'netsh interface teredo show state' or check Services for 'IP Helper' service status
    Affected if Teredo service is started and running
  2. Check Teredo interface configuration
    Run 'netsh interface ipv6 show interface' and look for 'Teredo Tunneling Pseudo-Interface' with state 'connected'
    Affected if Teredo interface exists and is in connected state
  3. Verify Teredo type and server
    Run 'netsh interface teredo show state' and note the Type (client/enterpriseclient) and Server IP configured
    Affected if Teredo is configured as a client connecting to a server, allowing incoming tunneled traffic
  4. Inspect trusted peer list
    Run 'netsh interface teredo show state' to see if any peers are listed as trusted. Check registry under HKLM\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\Teredo_Per_Interface for configured peers
    Affected if Trusted peer entries exist without validation that low 32 bits map to RFC1918 addresses

If Teredo service is enabled and connected (especially as a client), the system may be vulnerable to IPv4 traffic tunneling via crafted Teredo addresses with non-RFC1918 mapped low 32 bits.

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

Implement validation of the low 32 bits of incoming Teredo addresses to reject or mark untrusted any that map to RFC1918 private address space (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) or other non-routable addresses before creating trusted peer entries.

Fix this in Teredo Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,880
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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-2006-6264 in production — separate from our analysis above.

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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
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  • Version or environment caveats, and links to real fixes
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