CVE-2009-0561

CVE-2009-0561 is a critical-severity vulnerability in Microsoft Office with a CVSS 2.0 base score of 9.3. Its EPSS exploit-prediction score of 37% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-189.

Key facts

Description

Integer overflow in Excel in Microsoft Office 2000 SP3, Office XP SP3, Office 2003 SP3, and Office 2004 and 2008 for Mac; Excel in 2007 Microsoft Office System SP1 and SP2; Open XML File Format Converter for Mac; Microsoft Office Excel Viewer 2003 SP3; Microsoft Office Excel Viewer; Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2; and Microsoft Office SharePoint Server 2007 SP1 and SP2 allows remote attackers to execute arbitrary code via an Excel file with a Shared String Table (SST) record with a numeric field that specifies an invalid number of unique strings, which triggers a heap-based buffer overflow, aka "Record Integer Overflow Vulnerability."

Frequently asked questions

What is CVE-2009-0561?
Integer overflow in Excel in Microsoft Office 2000 SP3, Office XP SP3, Office 2003 SP3, and Office 2004 and 2008 for Mac; Excel in 2007 Microsoft Office System SP1 and SP2; Open XML File Format Converter for Mac; Microsoft Office Excel Viewer 2003 SP3; Microsoft Office Excel Viewer; Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2; and Microsoft Office SharePoint Server 2007 SP1 and SP2 allows remote attackers to execute arbitrary code via an Excel file with a Shared String Table (SST) record with a numeric field that specifies an invalid number of unique strings, which triggers a heap-based buffer overflow, aka "Record Integer Overflow Vulnerability."
How severe is CVE-2009-0561?
CVE-2009-0561 has a CVSS 2.0 base score of 9.3, rated critical severity.
Is CVE-2009-0561 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 37% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-0561?
CVE-2009-0561 primarily affects Microsoft Office. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-0561?
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-2009-0561 published?
CVE-2009-0561 was published on 2009-06-10 and last updated on 2026-06-16.

References

Affected products (16)

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