The LDAP service in Active Directory on Microsoft Windows 2000 SP4 does not properly free memory for LDAP and LDAPS requests, which allows remote attackers to execute arbitrary code via a request that uses hexadecimal encoding, whose associated memory is not released, related to a "DN AttributeValue," aka "Active Directory Invalid Free Vulnerability." NOTE: this issue is probably a memory leak.
Conclusion & alert: CVE-2009-1138 is rated High Risk (69.4/100): CVSS Critical severity, with high exploitation likelihood (EPSS 39.40%, 98th 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 | 58.55% | 39.40% | -19.15% |
| 2 | 2025-12-27 | 60.40% | 58.55% | -1.85% |
| 3 | 2025-10-23 | — | 60.40% | — |
Full EPSS history (32 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 10.0 | 2.0 | HIGH |
|
10.0 | 10.0 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| microsoft | windows_2000 | — | cpe:2.3:o:microsoft:windows_2000:*:sp4:*:*:*:*:*:* |