Vulnerability · Published Aug 13, 2026 · Assigned by VulnCheck
CVE-2026-53791rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header
Critical 9.1
In plain English
A critical-severity authentication bypass by spoofing in rsync from RsyncProject. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | rsync | 3.5.0-3.el10_2 | ALSA-2026:67463 |
| AlmaLinux:9 | rsync | 3.2.7-1.el9_8 | ALSA-2026:67462 |
| AlmaLinux:10 | rsync-daemon | 3.5.0-3.el10_2 | ALSA-2026:67463 |
| AlmaLinux:9 | rsync-daemon | 3.2.7-1.el9_8 | ALSA-2026:67462 |
| AlmaLinux:10 | rsync-rrsync | 3.5.0-3.el10_2 | ALSA-2026:67463 |
| AlmaLinux:9 | rsync-rrsync | 3.2.7-1.el9_8 | ALSA-2026:67462 |
| Alpine:v3.21 | rsync | 3.5.0-r0 | ALPINE-CVE-2026-53791 |
| Alpine:v3.22 | rsync | 3.5.0-r0 | ALPINE-CVE-2026-53791 |
| Alpine:v3.23 | rsync | 3.5.0-r0 | ALPINE-CVE-2026-53791 |
| Alpine:v3.24 | rsync | 3.5.0-r0 | ALPINE-CVE-2026-53791 |
| Debian:12 | rsync | no fix listed | DEBIAN-CVE-2026-53791 |
| Debian:13 | rsync | 3.5.0+ds1-0+deb13u1 | DEBIAN-CVE-2026-53791 |
| Debian:14 | rsync | 3.5.0+ds1-1 | DEBIAN-CVE-2026-53791 |
| Rocky Linux:10 | rsync | 0:3.5.0-3.el10_2 | RLSA-2026:67463 |
| Rocky Linux:9 | rsync | 0:3.2.7-1.el9_8 | RLSA-2026:67462 |
| Ubuntu:22.04:LTS | rsync | no fix listed | UBUNTU-CVE-2026-53791 |
| Ubuntu:24.04:LTS | rsync | no fix listed | UBUNTU-CVE-2026-53791 |
| Ubuntu:26.04:LTS | rsync | no fix listed | UBUNTU-CVE-2026-53791 |
| Ubuntu:26.10 | rsync | no fix listed | UBUNTU-CVE-2026-53791 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| RsyncProject | rsync | 0 – through 3.4.4 |
Weakness: CWE-290 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
References
- GitHub Security Advisory (GHSA-h2q9-5fr8-w635) vendor-advisory
- rsync 3.5.0 Release Notes release-notes
- https://www.vulncheck.com/advisories/rsync-daemon-ip-spoofing-via-proxy-protocol-header third-party-advisory