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CVE-2026-43617— Rsync < 3.4.3 Authorization Bypass via Hostname Resolution

Quick assessment

Affected
RsyncProject rsync
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Rsync是RsyncProject开源的一款快速且用途广泛的文件复制工具。用于远程文件和本地文件。 Rsync 3.4.2及之前版本存在安全漏洞，该漏洞源于基于主机名的访问控制列表在配置chroot时存在授权绕过，攻击者可通过控制PTR记录绕过基于主机名的拒绝规则。

CVSS 4.8 · Medium EPSS 0.32% · P22

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
RsyncProject rsync < 3.4.3 affected
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I. Basic Information for CVE-2026-43617

Vulnerability Information
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Vulnerability Title
Rsync < 3.4.3 Authorization Bypass via Hostname Resolution
Source: CVE Program / CVE List V5
Vulnerability Description
Rsync version 3.4.2 and prior contain an authorization bypass vulnerability in the rsync daemon's hostname-based access control list enforcement when configured with chroot. Attackers can bypass hostname-based deny rules by controlling the PTR record for their source IP address, allowing connections from hostnames that administrators intended to deny when reverse DNS resolution fails and defaults to UNKNOWN.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用候选名称进行的认证绕过
Source: CVE Program / CVE List V5
Vulnerability Title
Rsync 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Rsync是RsyncProject开源的一款快速且用途广泛的文件复制工具。用于远程文件和本地文件。 Rsync 3.4.2及之前版本存在安全漏洞，该漏洞源于基于主机名的访问控制列表在配置chroot时存在授权绕过，攻击者可通过控制PTR记录绕过基于主机名的拒绝规则。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
RsyncProject rsync 0 ~ 3.4.3 -

II. Public POCs for CVE-2026-43617

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III. Intelligence Information for CVE-2026-43617

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Vendor Advisories for CVE-2026-43617 (2)

Vendor Pages for CVE-2026-43617 (1)

Same Patch Batch · RsyncProject · 2026-05-20 · 6 CVEs total

CVE-2026-43618 8.1 HIGH Rsync < 3.4.3 Integer Overflow Information Disclosure
CVE-2026-29518 7.0 HIGH Rsync < 3.4.3 TOCTOU Race Condition Allows Symlink-Based Arbitrary File Write
CVE-2026-43620 6.5 MEDIUM Rsync < 3.4.3 Out-of-Bounds Array Read via recv_files()
CVE-2026-43619 6.3 MEDIUM Rsync < 3.4.3 Symlink Race Condition via Path-Based Syscalls
CVE-2026-45232 3.1 LOW Rsync < 3.4.3 Off-by-One Stack Write via HTTP Proxy

IV. Related Vulnerabilities

Same product: rsync
Same vendor: RsyncProject
Same weakness: CWE-289

V. Comments for CVE-2026-43617

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