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.
Conclusion & alert: CVE-2006-3551 is rated Low Risk (11.4/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.27%). Mandatory action: Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.07% | 0.27% | +0.20% |
| 2 | 2025-03-17 | 0.04% | 0.07% | +0.03% |
| 3 | 2023-03-07 | — | 0.04% | — |
Full EPSS history (4 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 1.2 | 2.0 | LOW |
|
1.9 | 2.9 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| ncp_network_communications | secure_client | <= 8.30_build_59 | cpe:2.3:a:ncp_network_communications:secure_client:*:*:*:*:*:*:*:* |