rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header (CVE-2026-53791) | HOL Guard CVE

Critical · CVSS 9.1CVE-2026-53791

rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header

Answer in brief

CVE-2026-53791 records a Critical severity (CVSS 9.1) vulnerability in rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header. The current sources do not mark it as known exploited. The current feed maps RsyncProject/rsync (generic), RsyncProject/rsync (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 13, 2026Updated Aug 31, 2026Source checked Sep 27, 2026First seen by HOL Aug 13, 2026Material review Aug 31, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.1
Exploitation: Not marked as known exploited
Affected software: 3 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps RsyncProject/rsync (generic), RsyncProject/rsync (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:a:samba:rsync::::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
RsyncProject/rsyncgeneric	0	Not reported
RsyncProject/rsyncgeneric	>=0 <=3.4.4	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for RsyncProject/rsync, RsyncProject/rsync.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 13, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 31, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 13, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.