Published May 20, 2026Sources checked Nov 11, 2026
9.8CRITICALCVSS out of 10
What this means
Review the available evidence
CVE-2026-3593 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: May 23, 2026
CBL-Mariner Releases
Vendor-listed releases
9.20.23-1
CISA KEVNot listedBased on the latest collected catalog
EPSS1.5%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-3593?
A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1.
BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.