How severe is CVE-2009-2509?

CVE-2009-2509 has a CVSS 2.0 base score of 9.0, rated critical severity.

Is CVE-2009-2509 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-2509?

CVE-2009-2509 primarily affects Microsoft Windows Server 2003. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-2509?

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-2009-2509 published?

CVE-2009-2509 was published on 2009-12-09 and last updated on 2026-06-16.

CVE-2009-2509

CVE-2009-2509 is a critical-severity vulnerability in Microsoft Windows Server 2003 with a CVSS 2.0 base score of 9.0. Its EPSS exploit-prediction score of 17% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Severity: Critical (CVSS 2.0 base score 9.0)
EPSS exploit prediction: 17% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Microsoft Windows Server 2003
Published: 2009-12-09
Last modified: 2026-06-16

Description

Active Directory Federation Services (ADFS) in Microsoft Windows Server 2003 SP2 and Server 2008 Gold and SP2 does not properly validate headers in HTTP requests, which allows remote authenticated users to execute arbitrary code via a crafted request to an IIS web server, aka "Remote Code Execution in ADFS Vulnerability."

Frequently asked questions

What is CVE-2009-2509?: Active Directory Federation Services (ADFS) in Microsoft Windows Server 2003 SP2 and Server 2008 Gold and SP2 does not properly validate headers in HTTP requests, which allows remote authenticated users to execute arbitrary code via a crafted request to an IIS web server, aka "Remote Code Execution in ADFS Vulnerability."
How severe is CVE-2009-2509?: CVE-2009-2509 has a CVSS 2.0 base score of 9.0, rated critical severity.
Is CVE-2009-2509 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-2509?: CVE-2009-2509 primarily affects Microsoft Windows Server 2003. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-2509?: 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-2009-2509 published?: CVE-2009-2509 was published on 2009-12-09 and last updated on 2026-06-16.

References

Affected products (5)

cpe:2.3:o:microsoft:windows_server_2003:*:sp2:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:*:*:x32:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:*:*:x64:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:*:sp2:x32:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:*:sp2:x64:*:*:*:*:*

More vulnerabilities in Microsoft Windows Server 2003

CVE-2015-0014 — Critical (CVSS 10.0): Buffer overflow in the Telnet service in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2…
CVE-2014-6321 — Critical (CVSS 10.0): Schannel in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1,…
CVE-2013-3195 — Critical (CVSS 10.0): The DSA_InsertItem function in Comctl32.dll in the Windows common control library in Microsoft Windows XP SP2, Windows…
CVE-2013-3175 — Critical (CVSS 10.0): Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1,…
CVE-2012-4786 — Critical (CVSS 10.0): The kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server…
CVE-2012-1851 — Critical (CVSS 10.0): Format string vulnerability in the Print Spooler service in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2,…

All CVEs affecting Microsoft Windows Server 2003 →

Other CWE-20 (Improper Input Validation) vulnerabilities

CVE-2026-48316 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48281 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48277 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48055 — Critical (CVSS 10.0): Streambert is a cross-platform Electron Desktop App to stream and download any video media. In versions 2.4.0 and…
CVE-2026-34910 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi OS…
CVE-2026-33587 — Critical (CVSS 10.0): Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and…

Browse all CWE-20 (Improper Input Validation) vulnerabilities →