Known exploited vulnerability
CVE-2009-0556
The short answer
CVE-2009-0556 affects n/a n/a and is rated high (CVSS 8.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-01-07: attackers are using it, so patch it first.
What it is
Microsoft Office PowerPoint 2000 SP3, 2002 SP3, and 2003 SP3, and PowerPoint in Microsoft Office 2004 for Mac, allows remote attackers to execute arbitrary code via a PowerPoint file with an OutlineTextRefAtom containing an an invalid index value that triggers memory corruption, as exploited in the wild in April 2009 by Exploit:Win32/Apptom.gen, aka "Memory Corruption Vulnerability."
Weakness: CWE-94.
Severity
8.8 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Jan 7, 2026
Federal due date Jan 28, 2026
EPSS, next 30 days
67%
Higher than 99% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Affected products
n/a. NVD's record lists the exact affected versions.
References
- docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-017 Vendor Advisory
- exchange.xforce.ibmcloud.com/vulnerabilities/49632 Third Party Advisory
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6204 Broken Link
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6279 Broken Link
- docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-017 Vendor Advisory
- exchange.xforce.ibmcloud.com/vulnerabilities/49632 Third Party Advisory
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6204 Broken Link
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6279 Broken Link
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2009-0556 US Government Resource
Questions
Is CVE-2009-0556 being exploited?
Yes. CISA added CVE-2009-0556 to its Known Exploited Vulnerabilities catalog on 2026-01-07, with a federal remediation due date of 2026-01-28.
How do I fix CVE-2009-0556?
CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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