Vulnerability in Rsyncproject Rsync
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 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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.007 (51.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 51.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
- Rsyncproject Rsync — versions 0, 3.5.0
- Samba Rsync
Weakness classification (CWE)
References
- github.com/RsyncProject/rsync/releases/tag/v3.5.0 (release-notes, Product, Release Notes)
- github.com/RsyncProject/rsync/security/advisories/GHSA-h2q9-5fr8-w635 (vendor-advisory, Vendor Advisory)
- www.vulncheck.com/advisories/rsync-daemon-ip-spoofing-via-proxy-protocol-header (Third Party Advisory, Release Notes, third-party-advisory)
Frequently asked questions
- What is CVE-2026-53791?
- CVE-2026-53791 is a critical-severity vulnerability in Rsyncproject Rsync, classified under Authentication Bypass by Spoofing. CVSS score: 9.1/10. Published 2026-08-13.
- How severe is CVE-2026-53791?
- Critical severity. CVSS v3 base score is 9.1 out of 10.