CVE-2001-1431
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 · uneditedNokia Firewall Appliances running IPSO 3.3 and VPN-1/FireWall-1 4.1 Service Pack 3, IPSO 3.4 and VPN-1/FireWall-1 4.1 Service Pack 4, and IPSO 3.4 or IPSO 3.4.1 and VPN-1/FireWall-1 4.1 Service Pack 5, when SYN Defender is configured in Active Gateway mode, does not properly rewrite the third packet of a TCP three-way handshake to use the NAT IP address, which allows remote attackers to gain sensitive information.
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 confidenceWhen Nokia Firewall Appliances running IPSO 3.3/3.4/3.4.1 with VPN-1/FireWall-1 4.1 have SYN Defender configured in Active Gateway mode, the firewall fails to rewrite the third packet (ACK) of a TCP three-way handshake to use the NAT-translated IP address, causing internal network information to leak to external attackers.
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= 4.1= 4.1= ipso_3.3= ipso_3.4= ipso_3.41CVSS 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
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:N/A:N
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 IPSO versionRun 'ipso -v' or check system information to determine the IPSO version numberAffected if Version is 3.3, 3.4, or 3.4.1 specifically (not later versions)
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Identify VPN-1/FireWall-1 versionRun 'fw ver' or check Checkpoint software version installed on the applianceAffected if Version is exactly 4.1
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Verify SYN Defender configurationCheck the firewall policy or configuration for SYN Defender settings - look for SYN Defender being enabled in the security policyAffected if SYN Defender is enabled in the firewall policy
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Confirm Active Gateway mode is in useExamine SYN Defender configuration parameters to determine if Active Gateway mode is configured rather than other modes like Standby or SYN ProxyAffected if SYN Defender is set to Active Gateway mode
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Check if NAT is configuredReview the firewall NAT rules or NAT configuration to see if address translation is activeAffected if NAT rules exist that would translate internal IP addresses to external addresses
The environment is affected only if running IPSO 3.3/3.4/3.4.1 with VPN-1/FireWall-1 4.1, SYN Defender is enabled in Active Gateway mode, AND NAT translation is configured - all conditions must be present.
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 the appropriate patched Service Pack for the IPSO version in use, or disable SYN Defender Active Gateway mode if patches are unavailable; consider migration off this legacy platform.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2001-1431 — 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-2001-1431 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
- No spam, self-promotion, credentials, or personal data