Critical severity · published Aug 13, 2026
CVE-2026-53791
rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header
9.1
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RS
rsync · RsyncProject
through 3.4.4 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53791
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-53791
Product
https://github.com/RsyncProject/rsync/releases/tag/v3.5.0
Vendor Advisory
https://github.com/RsyncProject/rsync/security/advisories/GHSA-h2q9-5fr8-w635
Release Notes
https://www.vulncheck.com/advisories/rsync-daemon-ip-spoofing-via-proxy-protocol-header
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