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1.2

NCP Secure Enterprise Client permits forged DHCP traffic

CVE-2006-3551 · published 20 years ago
Summary

The NCP Secure Enterprise Client can be tricked into sending and receiving DHCP‑style UDP packets even when its firewalls are set to block all traffic. This loophole could let an attacker manipulate network settings or bypass the intended block. Apply the latest software update and review firewall rules to ensure such traffic is not allowed.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
ncp_network_communications secure_client <= 8.30_build_59
cpe:2.3:a:ncp_network_communications:secure_client:*:*:*:*:*:*:*:*
Original advisory text
NCP Secure Enterprise Client (aka VPN/PKI client) 8.30 Build 59, and possibly earlier versions, when the Link Firewall and Personal Firewall are both configured to block all inbound and outbound ne...
NCP Secure Enterprise Client (aka VPN/PKI client) 8.30 Build 59, and possibly earlier versions, when the Link Firewall and Personal Firewall are both configured to block all inbound and outbound network traffic, allows context-dependent attackers to send inbound UDP traffic with source port 67 and destination port 68, and outbound UDP traffic with source port 68 and destination port 67.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit (estimated)
  • Gives an attacker partial control (estimated)
Severity
1.2 Low
Exploitation
<1% chance of attack within 30 days
Timeline
Published13 Jul 2006
Updated4 Nov 2026
First seen29 Sep 2026
Sources
CVE-2006-3551 · NVD
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