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

• https://nvd.nist.gov/vuln/detail/CVE-2006-3551
• https://exchange.xforce.ibmcloud.com/vulnerabilities/27484
• http://lists.grok.org.uk/pipermail/full-disclosure/2006-June/047547.html