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CVE-2026-8398

Critical CVSS 9.8 Known exploited

Published 2026-05-15 · last changed 2026-06-17 · added to CISA KEV 2026-05-27

This one is being exploited in the wild.

CISA added CVE-2026-8398 to the Known Exploited Vulnerabilities catalog on 2026-05-27. Federal agencies are required to remediate it on a deadline. If you have affected machines, this is the class of finding that moves ahead of the rest of the queue.

The fix

We hold no Microsoft remediation data for CVE-2026-8398, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

A supply chain attack compromised the official installation packages of DAEMON Tools Lite (Windows versions 12.5.0.2421 through 12.5.0.2434), distributed from the legitimate website daemon-tools.cc between approximately April 8, 2026, and May 5, 2026. Attackers gained unauthorized access to the vendor's (AVB Disc Soft) build or distribution infrastructure and trojanized three binaries: DTHelper.exe, DiscSoftBusServiceLite.exe, and DTShellHlp.exe. These files were digitally signed with the legitimate AVB Disc Soft code-signing certificate, allowing the malicious installers to appear trustworthy and bypass signature-based detection.

Sources

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H