CVE-2006-1651

Microsoft ISA Server 2004 allows remote attackers to bypass certain filtering rules, including ones for (1) ICMP and (2) TCP, via IPv6 packets. NOTE: An established researcher has disputed this issue, saying that "Neither ISA Server 2004 nor Windows 2003 Basic Firewall support IPv6 filtering ... This is different network protocol.

Published: 2006-04-06 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2006-1651 is rated High Risk (68.7/100): CVSS High severity, with high exploitation likelihood (EPSS 15.19%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +8.92% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2006-1651

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 6.26% 15.19% +8.92%
2 2026-05-05 10.82% 6.26% -4.56%
3 2026-01-02 — 10.82% —

Full EPSS history (20 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2006-1651

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2006-1651

OS Trackers for CVE-2006-1651

vendor priority summary link
alpine — CVE-2006-1651: no source package rows; 0 state rows across 0 repos (none); fixed 0, open 0. https://security.alpinelinux.org/vuln/CVE-2006-1651

NVD evaluator notes for CVE-2006-1651

Solution: This vulnerability has been disputed.

Affected software / configurations for CVE-2006-1651

Vendor Product Version Raw CPE
microsoft isa_server 2004 cpe:2.3:a:microsoft:isa_server:2004:*:*:*:*:*:*:*

References for CVE-2006-1651

cvelogic Threat Intelligence