Vpn ClientApplication · Cisco
CVE-2002-1104
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 · uneditedCisco Virtual Private Network (VPN) Client software 2.x.x and 3.x before 3.0.5 allows remote attackers to cause a denial of service (crash) via TCP packets with source and destination ports of 137 (NETBIOS).
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 Cisco VPN Client versions 2.x and 3.x before 3.0.5 contains a denial of service vulnerability where specially crafted TCP packets with both source and destination ports set to 137 (NETBIOS) can cause the client software to crash.
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
Vpn ClientApplication
= 2.0= 3.0CVSS 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
- Partial
AV:N/AC:L/Au:N/C:N/I:N/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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Check installed Cisco VPN Client versionOpen Windows Control Panel > Programs and Features (or Run > appwiz.cpl), find Cisco VPN Client in the list and note the version. Alternatively, check the About dialog in the VPN Client software or inspect the executable file properties of vpnclient.exe in the installation directory.Affected if Version is 2.0, 3.0, or any 2.x/3.x version earlier than 3.0.5
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Verify if NETBIOS over TCP/IP is enabledOn the Windows machine running the VPN Client, open Network Connections > right-click the VPN adapter > Properties > double-click Internet Protocol (TCP/IP) > click Advanced > go to the WINS tab and check if 'Enable NETBIOS over TCP/IP' is selected.Affected if NETBIOS over TCP/IP is enabled on the VPN adapter (the vulnerability requires NETBIOS port 137 traffic to reach the client)
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Check VPN client configuration for NETBIOS settingsInspect the VPN Client profile configuration files (.pcf files) for entries related to 'NetBIOS' or 'EnableMSNetBIOS'. These are typically located in the profiles directory under the VPN Client installation folder.Affected if NETBIOS support is enabled in the VPN profile configuration
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Monitor for port 137 TCP trafficUse Windows Firewall logging, a network sniffer (such as Wireshark), or the VPN Client's diagnostic logs to observe whether incoming TCP packets with both source and destination port set to 137 are reaching the client.Affected if TCP port 137 traffic is allowed through to the VPN client interface (the vulnerability is triggered by such traffic)
You are affected if the Cisco VPN Client version is 2.0, 3.0, or any 2.x/3.x version prior to 3.0.5 AND NETBIOS over TCP/IP is enabled on the VPN adapter, allowing port 137 traffic to reach the client.
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 dataUpgrade to Cisco VPN Client version 3.0.5 or later. Additionally, network-level filtering to block TCP port 137 traffic can provide defense-in-depth protection.
Fix this in Vpn Client
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2002-1104 — 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-2002-1104 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
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