FreeBSDOperating system
CVE-1999-0074
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 · uneditedListening TCP ports are sequentially allocated, allowing spoofing attacks.
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 confidenceOn affected systems, when services bind to listening TCP ports, the ports were allocated sequentially from a predictable range. This predictability allows attackers to anticipate which port a service will use, enabling TCP spoofing attacks where malicious packets can be crafted to impersonate legitimate services or hijack connections.
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
FreeBSDOperating system
= 6.2
Linux KernelOperating system
= 2.6.20.1all versions= 2.0.4CVSS 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
- None
AV:N/AC:L/Au:N/C:P/I:P/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 operating system and versionRun 'uname -a' on Linux/BSD or 'systeminfo' on Windows to determine the exact OS version and build numberAffected if The system is FreeBSD 6.2 or earlier, Linux Kernel 2.6.20.1 or earlier, any version of Windows NT, or NetBSD 2.0.4 or earlier
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Check ephemeral port range allocation methodOn Linux, examine /proc/sys/net/ipv4/ip_local_port_range to see the port range. On Windows, use 'netsh int ipv4 show dynamicport tcp'. On BSD systems, check sysctl net.inet.ip.portrange valuesAffected if The port range is sequential with no randomization or the range values indicate legacy sequential allocation (typical default before randomization was implemented)
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Verify if port randomization is enabledFor Linux kernels 2.6.20.2 and later, check if the 'ip_local_port_range' has been randomized or if /proc/sys/net/ipv4/ip_local_port_range is non-contiguous. For Windows, check if 'netsh int tcp show global' shows randomized port allocationAffected if Port randomization is not enabled and the system still uses predictable sequential port selection for binding services
The system is affected if it runs an older OS version known to use sequential TCP port allocation, and the port range configuration shows predictable/sequential port selection without randomization.
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 dataModern operating systems have addressed this by randomizing ephemeral port allocation. For legacy systems, implement network segmentation, use fixed well-known ports for critical services, and enforce proper TCP authentication mechanisms like TCP MD5 signatures (RFC 2385) or IPsec.
Fix this in FreeBSD
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing1.0 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 $1,456.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-1999-0074 — 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-1999-0074 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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