What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-13 · updated 2026-10-24
• Weakness: CWE-290

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 products

• RsyncProject rsync: before 3.5.0 — fixed in 3.5.0

How to fix

Upgrade to a fixed version: RsyncProject rsync 3.5.0. Check the vendor advisory for mitigations.

References

• https://github.com/RsyncProject/rsync/releases/tag/v3.5.0
• https://github.com/RsyncProject/rsync/security/advisories/GHSA-h2q9-5fr8-w635
• https://www.vulncheck.com/advisories/rsync-daemon-ip-spoofing-via-proxy-protocol-header

Get alerted when CVE-2026-53791 or the next vulnerability affects your stack