Published May 20, 2026Sources checked Nov 11, 2026
4.8MEDIUMCVSS out of 10
What this means
Review the available evidence
CVE-2026-43617 and is rated Medium severity with a CVSS score of 4.8. 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
3.4.3-1
CISA KEVNot listedBased on the latest collected catalog
EPSS0.3%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-43617?
Rsync version 3.4.2 and prior contain an authorization bypass vulnerability in the rsync daemon's hostname-based access control list enforcement when configured with chroot. Attackers can bypass hostname-based deny rules by controlling the PTR record for their source IP address, allowing connections from hostnames that administrators intended to deny when reverse DNS resolution fails and defaults to UNKNOWN.