This page tracks the Ubuntu fix status. The vulnerability itself is described on the main CVE page. View CVE-2026-53791 →

UBUNTU-CVE-2026-53791

rsync daemon before 3.5.0 contains an IP address spoofing vulnerability that allows unauthenticated remote attackers to bypass IP-based access control...

Original description

The description as published by the source.

rsync daemon before 3.5.0 contains an IP address spoofing vulnerability that allows unauthenticated remote attackers to bypass IP-based access controls by sending a crafted PROXY protocol header with a forged source address. Attackers who can connect directly to the rsync daemon can inject a spoofed source IP in the PROXY protocol header to circumvent hosts allow/deny rules, gaining unauthorized access that would otherwise be blocked based on their real source address.

Source: OSV.dev (Open Source Vulnerabilities) OSV