How severe is CVE-2009-2505?

CVE-2009-2505 has a CVSS 2.0 base score of 10.0, rated critical severity.

Is CVE-2009-2505 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 32% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-2505?

CVE-2009-2505 primarily affects Microsoft Windows Server 2008. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-2505?

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-2009-2505 published?

CVE-2009-2505 was published on 2009-12-09 and last updated on 2026-06-16.

CVE-2009-2505

CVE-2009-2505 is a critical-severity vulnerability in Microsoft Windows Server 2008 with a CVSS 2.0 base score of 10.0. Its EPSS exploit-prediction score of 32% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 2.0 base score 10.0)
EPSS exploit prediction: 32% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Microsoft Windows Server 2008
Published: 2009-12-09
Last modified: 2026-06-16

Description

The Internet Authentication Service (IAS) in Microsoft Windows Vista SP2 and Server 2008 SP2 does not properly validate MS-CHAP v2 Protected Extensible Authentication Protocol (PEAP) authentication requests, which allows remote attackers to execute arbitrary code via crafted structures in a malformed request, aka "Internet Authentication Service Memory Corruption Vulnerability."

Frequently asked questions

What is CVE-2009-2505?: The Internet Authentication Service (IAS) in Microsoft Windows Vista SP2 and Server 2008 SP2 does not properly validate MS-CHAP v2 Protected Extensible Authentication Protocol (PEAP) authentication requests, which allows remote attackers to execute arbitrary code via crafted structures in a malformed request, aka "Internet Authentication Service Memory Corruption Vulnerability."
How severe is CVE-2009-2505?: CVE-2009-2505 has a CVSS 2.0 base score of 10.0, rated critical severity.
Is CVE-2009-2505 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 32% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-2505?: CVE-2009-2505 primarily affects Microsoft Windows Server 2008. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-2505?: 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-2009-2505 published?: CVE-2009-2505 was published on 2009-12-09 and last updated on 2026-06-16.

References

Affected products (4)

cpe:2.3:o:microsoft:windows_server_2008:*:sp2:itanium:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:sp2:x32:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:sp2:x64:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_vista:*:sp2:*:*:*:*:*:*

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