Microsoft · DirectX · Microsoft DirectX NULL Byte Overwrite Vulnerability
Verdict
Patch first · actively exploited, reachable from the internet without credentials, and in the top 5% of CVEs by near-term exploitation probability
Added to CISA KEV 2026-05-20 · exploited in the wild for 130 days
CVSS 8.8 HIGH. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.
| Attack vector | networkreachable over the network, with no local access needed |
|---|---|
| Privileges required | noneneeds no credentials at all |
| User interaction | requiredneeds a user to click, load or submit something first |
| Base vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| Weakness | CWE-158 |
This describes the vulnerability. It says nothing about whether your systems run it.
EPSS puts the probability of exploitation in the next 30 days at 0.5121, which places it in the top 5% of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.
| EPSS probability | 0.5121 |
|---|---|
| Percentile | 0.989 — top 5% |
| Added to KEV | 2026-05-20 |
|---|---|
| Days exploited | 130 |
| Federal remediation due | not set |
| Ransomware use | no known ransomware campaign use |
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Unspecified vulnerability in the QuickTime Movie Parser Filter in quartz.dll in DirectShow in Microsoft DirectX 7.0 through 9.0c on Windows 2000 SP4, Windows XP SP2 and SP3, and Windows Server 2003 SP2 allows remote attackers to execute arbitrary code via a crafted QuickTime media file, as exploited in the wild in May 2009, aka "DirectX NULL Byte Overwrite Vulnerability."