CVE-2026-70453

A flaw was found in rsync. A remote attacker can exploit an algorithmic complexity vulnerability within the hash_search() function by sending a specially crafted file list. This can lead to the exhaustion of the receiver's CPU resources, causing a sustained denial of service (DoS).

This Moderate flaw in rsync's hash_search() function allows a remote attacker to cause a denial of service. By sending a specially crafted file list, an attacker can exhaust the receiver's CPU resources, leading to service unavailability. This is particularly relevant in Red Hat environments where rsync is used for remote file synchronization and may be exposed to untrusted networks.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Disable unused rsyncd services (systemctl disable --now rsyncd), or restrict daemon access to trusted clients via hosts allow and firewall rules. Avoid synchronizing with untrusted senders or pushing to untrusted receivers and upload modules to prevent processing malicious file lists. To contain potential Denial of Service, enforce CPU resource limits on rsync processes using systemd cgroups or ulimit -t to prevent a quadratic search walk from starving the host.