CVE-2005-3945
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 · uneditedThe SynAttackProtect protection in Microsoft Windows 2003 before SP1 and Windows 2000 before SP4 with Update Roll-up uses a hash of predictable data, which allows remote attackers to cause a denial of service (CPU consumption) via a flood of SYN packets that produce identical hash values, which slows down the hash table lookups.
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 confidenceThe SynAttackProtect feature in Windows 2003 before SP1 and Windows 2000 before the Update Roll-up uses a weak hash function for SYN flood protection. Attackers can send SYN packets with predictable data that produces identical hash values, causing hash table collision degradation and high CPU consumption on the target system.
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 dataall versions= enterprise= r2= standard= webCVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify the installed Windows versionRun 'winver' or check System Properties to confirm if the system is Windows 2000 or Windows 2003 Server (any edition)Affected if The version is Windows 2000 (any version) or Windows 2003 Server before Service Pack 1
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Check Windows 2003 Service Pack levelRun 'winmsd' or check System Information for the Service Pack value. Alternatively, run 'systeminfo | findstr /C:"Service Pack"'Affected if Service Pack is not installed or is earlier than Service Pack 1 on Windows 2003
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Check Windows 2000 Update Roll-up statusCheck Add/Remove Programs for 'Update Rollup for Windows 2000 SP4' or examine the system for installed updatesAffected if The Update Roll-up for Windows 2000 SP4 is not installed
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Verify SynAttackProtect is enabledExamine the registry key HKLM\System\CurrentControlSet\Services\Tcpip\Parameters\SynAttackProtect. If the value exists and is set to a non-zero value (typically 1 or 2), SYN flood protection is activeAffected if The SynAttackProtect registry value exists and is set to 1 or higher (protection enabled)
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Confirm TCP/IP filtering is in default stateReview HKLM\System\CurrentControlSet\Services\Tcpip\Parameters\EnableSecurityFilters - if set to default (0) or not present, default SYN protection behavior appliesAffected if TCP/IP security filters are not configured to override the default SYN protection behavior
A system is affected if it runs Windows 2000 (any version without the Update Roll-up) or Windows 2003 Server (pre-SP1) and has SynAttackProtect enabled in the registry, allowing attackers to trigger hash collision degradation.
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 dataApply Windows 2003 Service Pack 1 or later, and the Windows 2000 Update Roll-up. Alternatively, upgrade to a supported Windows version with modern TCP/IP stack protection.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2005-3945 — 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-2005-3945 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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