Improper access control in Rsync - CVE-2026-43617
Published: June 1, 2026
Vulnerability identifier: #VU133145
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-43617
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Samba
Affected software:
Rsync
Rsync
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass hostname-based access controls.
The vulnerability exists due to improper access control in reverse-DNS lookup handling in rsync daemon mode when processing connections after entering the daemon chroot. A remote attacker can connect from a denied hostname and cause hostname-based deny rules to fail open to bypass hostname-based access controls.
Only daemon configurations with daemon chroot = /X are affected when the chroot tree lacks DNS resolution support. IP-based ACLs are unaffected.
How to mitigate CVE-2026-43617
Install security update from vendor's website.