CVE-2026-53791 rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header

What is CVE-2026-53791?

CVE-2026-53791 is a critical authentication bypass vulnerability in RsyncProject rsync, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-290

Which versions are affected by CVE-2026-53791?

It affects 1 product.

Products include Samba Rsync.

How do I fix CVE-2026-53791?

Upgrade to a fixed version.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-53791 being exploited?

There is no known exploitation of CVE-2026-53791 in the wild and no public exploit code.

Other vulnerabilities in RsyncProject rsync

• CVE-2017-15994 Security feature bypass in n/a Critical 9.8
• CVE-2026-70461 rsync 3.2.5 < 3.5.0 Heap Out-of-Bounds Write via files-from Entry High 8.8
• CVE-2026-70455 rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion High 8.7
• CVE-2026-70463 rsync 3.1.0 < 3.5.0 Authorization Bypass via auth users Directive Parsing High 8.6
• CVE-2026-53803 rsync < 3.5.0 Symlink Following Arbitrary File Overwrite High 8.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2026-53791, AZL-95783, BELL-CVE-2026-53791, DEBIAN-CVE-2026-53791, ECHO-9e2f-c214-61ad, GHSA-h2q9-5fr8-w635 and 2 more.