Exploited vulnerability · CISA KEV

Is CVE-2009-1537 exploited? Yes: in CISA KEV since 20 May 2026

Gociux · Microsoft DirectX · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2009-1537, Microsoft DirectX NULL Byte Overwrite Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 20 May 2026, 6200 days after it was published. It affects Microsoft DirectX. If you run it, CISA's required action is: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What it is

Microsoft DirectX contains a NULL byte overwrite vulnerability in the QuickTime Movie Parser Filter in quartz.dll in DirectShow which could allow remote attackers to execute arbitrary code via a crafted QuickTime media file.

What to do

1. Check whether you run it. Look for DirectX in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
2. Apply the fix. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 29 May 2009.
4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

References

• learn.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-028
• nvd.nist.gov/vuln/detail/CVE-2009-1537

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in May 2026 · Microsoft scorecard · act-now radar.