How severe is CVE-2009-1138?

CVE-2009-1138 has a CVSS 2.0 base score of 10.0, rated critical severity.

Is CVE-2009-1138 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 39% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-1138?

CVE-2009-1138 affects Microsoft Windows 2000. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2009-1138?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2009-1138 published?

CVE-2009-1138 was published on 2009-06-10 and last updated on 2026-06-16.

CVE-2009-1138

CVE-2009-1138 is a critical-severity vulnerability in Microsoft Windows 2000 with a CVSS 2.0 base score of 10.0. Its EPSS exploit-prediction score of 39% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-399.

Key facts

Severity: Critical (CVSS 2.0 base score 10.0)
EPSS exploit prediction: 39% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-399
Affected product: Microsoft Windows 2000
Published: 2009-06-10
Last modified: 2026-06-16

Description

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.

Frequently asked questions

What is CVE-2009-1138?: 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.
How severe is CVE-2009-1138?: CVE-2009-1138 has a CVSS 2.0 base score of 10.0, rated critical severity.
Is CVE-2009-1138 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 39% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-1138?: CVE-2009-1138 affects Microsoft Windows 2000. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2009-1138?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2009-1138 published?: CVE-2009-1138 was published on 2009-06-10 and last updated on 2026-06-16.

References

Affected products (1)

cpe:2.3:o:microsoft:windows_2000:*:sp4:*:*:*:*:*:*

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