Not Failing Securely ('Failing Open') in Rsync - CVE-2026-70452
Published: August 13, 2026
Vulnerability identifier: #VU142266
CSH Severity: Medium
CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-70452
CWE-ID: CWE-636
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass host-based access restrictions and gain unauthorized access.
The vulnerability exists due to not failing securely in hosts deny access control processing when performing a forward DNS lookup of a configured hostname token. A remote attacker can connect from a host that should be denied to bypass host-based access restrictions and gain unauthorized access.
The issue occurs when forward lookup is enabled and a hostname token in hosts deny cannot be resolved, including during transient resolver failures or when a global daemon chroot lacks resolver configuration.
Affected software
Rsync
How to mitigate CVE-2026-70452
Install security update from vendor's website.
Rsync - update to 3.5.0