CVE-2009-0901

CVE-2009-0901 is a high-severity vulnerability in Microsoft Visual C++ with a CVSS 3.x base score of 8.8. Its EPSS exploit-prediction score of 42% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-94.

Key facts

Description

The Active Template Library (ATL) in Microsoft Visual Studio .NET 2003 SP1, Visual Studio 2005 SP1 and 2008 Gold, and Visual C++ 2005 SP1 and 2008 Gold and SP1; and Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, and Server 2008 Gold and SP2; does not prevent VariantClear calls on an uninitialized VARIANT, which allows remote attackers to execute arbitrary code via a malformed stream to an ATL (1) component or (2) control, related to ATL headers and error handling, aka "ATL Uninitialized Object Vulnerability."

Frequently asked questions

What is CVE-2009-0901?
The Active Template Library (ATL) in Microsoft Visual Studio .NET 2003 SP1, Visual Studio 2005 SP1 and 2008 Gold, and Visual C++ 2005 SP1 and 2008 Gold and SP1; and Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, and Server 2008 Gold and SP2; does not prevent VariantClear calls on an uninitialized VARIANT, which allows remote attackers to execute arbitrary code via a malformed stream to an ATL (1) component or (2) control, related to ATL headers and error handling, aka "ATL Uninitialized Object Vulnerability."
How severe is CVE-2009-0901?
CVE-2009-0901 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2009-0901 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 42% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-0901?
CVE-2009-0901 primarily affects Microsoft Visual C++. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-0901?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2009-0901 published?
CVE-2009-0901 was published on 2009-07-29 and last updated on 2026-06-16.

References

Affected products (8)

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