CVE-2006-1651
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 · uneditedMicrosoft ISA Server 2004 allows remote attackers to bypass certain filtering rules, including ones for (1) ICMP and (2) TCP, via IPv6 packets. NOTE: An established researcher has disputed this issue, saying that "Neither ISA Server 2004 nor Windows 2003 Basic Firewall support IPv6 filtering ... This is different network protocol.
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 · moderate confidenceMicrosoft ISA Server 2004 fails to properly filter IPv6 packets, allowing attackers to bypass configured filtering rules for ICMP and TCP traffic by transmitting malicious IPv6 traffic. The vulnerability exists because ISA Server 2004 was not designed to handle IPv6 filtering, potentially permitting unfiltered network communication.
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= 2004CVSS 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 checksWork through these to decide whether this CVE applies to you.
-
Verify ISA Server 2004 is installedCheck the installed programs list in Windows Control Panel or run 'appwiz.cpl' to locate Microsoft ISA Server and confirm the version is 2004Affected if The product Microsoft ISA Server 2004 is present on the system
-
Identify IPv6-enabled network interfacesOn the ISA Server machine, open Network Connections and examine each network adapter. Check the adapter properties for IPv6 protocol binding, or run 'netsh interface ipv6 show interface' to list active IPv6 interfacesAffected if Any network adapter connected to the internal or external network has IPv6 protocol enabled and bound
-
Confirm lack of IPv6 filtering rulesOpen ISA Server Management console, expand 'Firewall Policy', and review the rule set. Look for any rules explicitly referencing IPv6 protocol or ICMPv6/TCPv6 traffic typesAffected if No rules explicitly filter or block IPv6, ICMPv6, or TCP over IPv6 traffic, and IPv6 is enabled on network interfaces
-
Check if IPv6 traffic can traverse the ISA ServerReview the ISA Server network rules and topology configuration to determine whether IPv6 packets from external networks can be routed to internal networks behind the ISA ServerAffected if IPv6 traffic from external networks can reach internal protected networks without ISA Server filtering
A system is affected if Microsoft ISA Server 2004 is deployed and IPv6 traffic (ICMPv6 or TCP over IPv6) can pass through or around the ISA Server without being filtered, due to the product lacking IPv6 filtering capability.
Generated from the published advisory. Verify against your own configuration.
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 dataOrganizations should upgrade from ISA Server 2004 to a modern version with full IPv6 filtering support, or implement additional network-layer controls (such as host-based firewalls or perimeter filters) that explicitly handle IPv6 traffic to block malicious packets.
- Consultation8.0 h
- Implementation24.0 h
- Testing16.0 h
- Review / QA8.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $15,616.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2006-1651 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2006-1651 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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