Note: This vulnerability (CVE-2009-0238) was originally published in 2009, however CISA added it to the Known Exploited Vulnerabilities (KEV) catalog on 2026-04-14 due to detected active exploitation.
EPSS Alert: The probability of this vulnerability being exploited in the next 30 days is 57.2% (percentile: 98%).
Summary
| Parameter | Value |
|---|---|
| CVE ID | CVE-2009-0238 |
| Alert Source | CISA KEV - Active Exploitation |
| CVE Publication Year | 2009 |
| Date Published | 2026-04-14 |
| Vendor | Microsoft |
| Product | Office |
| CVSS Score | 9.3 (critical) |
| EPSS Score | 57.2% (percentile: 98%) |
| CISA KEV | Yes - confirmed active exploitation |
| Ransomware | Not confirmed |
| Remediation Deadline | 2026-04-28 |
Vulnerability Description
Microsoft Office Excel contains a remote code execution vulnerability that could allow an attacker to take complete control of an affected system if a user opens a specially crafted Excel file that includes a malformed object.
Required Actions
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Who Is Affected?
This vulnerability affects Office by Microsoft. Check if your organization uses this software and requires updates.
Sources
Need help securing your systems? nFlo team offers vulnerability management and 24/7 SOC services. Contact us.
How can nFlo help?
If your organization uses products affected by this vulnerability, contact us. We can help with:
- Verifying whether your systems are at risk
- Implementing patches and risk mitigation
- Monitoring for exploitation attempts in your environment
Useful resources:
- Active Directory security audit
- Incident response management
- SOC — Security Operations Center
- nFlo penetration testing
