CVE-2006-3652
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 Internet Security and Acceleration (ISA) Server 2004 allows remote attackers to bypass file extension filters via a request with a trailing "#" character. NOTE: as of 20060715, this could not be reproduced by third parties.
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 · low confidenceMicrosoft ISA Server 2004 fails to properly filter file extensions when a request contains a trailing '#' character. The '#' character acts as a URL fragment identifier, potentially causing the server to not process the extension for filtering purposes, allowing attackers to bypass extension-based blocking rules.
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.
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Confirm ISA Server 2004 is installedCheck the installed programs or services list on the server for Microsoft ISA Server 2004. Look in Programs and Features or check services.msc for the ISA Server service.Affected if The system has Microsoft ISA Server 2004 installed and running
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Verify the exact ISA Server versionOpen ISA Server Management, navigate to the server node, and check the version information in the right panel. Confirm it shows version 2004 specifically.Affected if The version shows exactly 2004 rather than a later version like ISA Server 2006 or Threat Management Gateway (TMG)
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Identify extension blocking rulesIn ISA Server Management, expand the firewall policy and review rule sets. Look for rules configured with URL sets or extension-based filtering, particularly rules that block specific file extensions like .exe, .asp, or .bat.Affected if Extension-based filtering or URL set rules are configured and active in the firewall policy
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Test the fragment identifier bypassSend a test HTTP request to the ISA Server from an external client using a URL with a blocked extension followed by a trailing '#' character, such as http://target/server.exe# or http://target/page.asp#. Monitor whether the request is allowed through when it should be blocked.Affected if Requests with blocked extensions bypass filtering when a trailing '#' character is appended to the URL
A user is affected if they run Microsoft ISA Server 2004 with active extension-based blocking rules that can be bypassed by appending a '#' character to URLs containing blocked file extensions.
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 dataSince ISA Server 2004 is end-of-life and this bypass could not be reproduced by third parties, migrate to supported Microsoft networking solutions (e.g., Azure Firewall, Microsoft Defender for Cloud Apps) or implement additional perimeter filtering capable of handling fragment identifiers consistently.
- Consultation8.0 h
- Implementation24.0 h
- Testing12.0 h
- Review / QA8.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2006-3652 — 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-2006-3652 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
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- 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
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