The server in Microsoft Active Directory on Windows Server 2003 SP2 does not properly handle an update request for a service principal name (SPN), which allows remote attackers to cause a denial of service (authentication downgrade or outage) via a crafted request that triggers name collisions, aka "Active Directory SPN Validation Vulnerability."
Conclusion & alert: CVE-2011-0040 is rated Moderate Risk (49.1/100): CVSS Medium severity, with high exploitation likelihood (EPSS 22.76%, 97th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. Mandatory action: 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.
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 | 35.77% | 22.76% | -13.01% |
| 2 | 2026-06-14 | 40.23% | 35.77% | -4.46% |
| 3 | 2025-05-29 | — | 40.23% | — |
Full EPSS history (11 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 5.0 | 2.0 | MEDIUM |
|
10.0 | 2.9 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| microsoft | windows_2003_server | — | cpe:2.3:o:microsoft:windows_2003_server:*:sp2:*:*:*:*:*:* |
| microsoft | windows_2003_server | — | cpe:2.3:o:microsoft:windows_2003_server:*:sp2:itanium:*:*:*:*:* |
| microsoft | windows_2003_server | — | cpe:2.3:o:microsoft:windows_2003_server:*:sp2:x64:*:*:*:*:* |