CVE-1999-1336
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 · unedited3Com HiPer Access Router Card (HiperARC) 4.0 through 4.2.29 allows remote attackers to cause a denial of service (reboot) via a flood of IAC packets to the telnet port.
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 confidence3Com HiPer Access Router Card (HiperARC) versions 4.0 through 4.2.29 contain a denial-of-service vulnerability in the telnet service. Remote attackers can cause device reboot by sending a flood of IAC (Telnet Interpret As Command) packets to the telnet port, likely due to improper handling of excessive IAC sequences.
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<= 4.2.29CVSS 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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Confirm device model is 3Com HiperARCIdentify whether the target device is a 3Com HiPer Access Router (HiperARC). Check the physical device label, management interface, or use SNMP to query the device sysDescr or sysObjectID.Affected if The device is a 3Com HiperARC or HiperARC-compatible router
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Determine installed firmware versionAccess the device administrative interface (web GUI, console, or CLI) and locate the system information or firmware version section. The exact location varies by device interface but is typically under 'System', 'Status', or 'Diagnostics'.Affected if The firmware version is 4.0, 4.1, 4.2, or any version up to and including 4.2.29
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Verify telnet service is enabledCheck the device configuration for telnet service settings. This is usually found in the device security, access control, or services configuration section.Affected if Telnet service (TCP port 23) is enabled on the device
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Assess telnet network exposureDetermine if telnet port TCP 23 is reachable from untrusted networks. Test with a telnet client attempt from an external host or review firewall/ACL rules protecting the device.Affected if Telnet port 23 is accessible from network segments outside the trusted management network
The environment is affected if it contains a 3Com HiperARC device running firmware version 4.2.29 or lower with telnet service enabled and reachable from an attacker's network location.
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 dataDisable telnet access on affected devices or block telnet port (TCP 23) at the network perimeter. Given the age of these devices (1990s era), consider replacement with current supported hardware as the definitive remediation.
- Consultation2.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-1999-1336 — 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-1999-1336 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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