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CVE-2026-29518— Rsync < 3.4.3 TOCTOU Race Condition Allows Symlink-Based Arbitrary File Write

Quick assessment

Affected
RsyncProject rsync
Exploitation
Public or AI PoC available; prioritize validation
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 3.4.3之前版本存在安全漏洞，该漏洞源于守护进程文件处理中存在检查时间与使用时间竞争条件，可能导致攻击者通过符号链接替换父目录组件将文件写入重定向到预期目录之外。具有模块路径写入权限的攻击者可利用此竞争条件创建或覆盖任意文件，当守护进程以高权限运行时可能修改敏感系统文件并实现权限提升。

CVSS 7.0 · High EPSS 0.14% · P3

Affected Version Matrix 1

VendorProduct Version RangeStatus
RsyncProject rsync < 3.4.3 affected
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I. Basic Information for CVE-2026-29518

Vulnerability Information
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Vulnerability Title
Rsync < 3.4.3 TOCTOU Race Condition Allows Symlink-Based Arbitrary File Write
Source: CVE Program / CVE List V5
Vulnerability Description
Rsync versions before 3.4.3 contain a time-of-check to time-of-use (TOCTOU) race condition in daemon file handling that allows attackers to redirect file writes outside intended directories by replacing parent directory components with symbolic links. Attackers with write access to a module path can exploit this race condition to create or overwrite arbitrary files, potentially modifying sensitive system files and achieving privilege escalation when the daemon runs with elevated privileges. This vulnerability can only be triggered if the chroot setting is false.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
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 3.4.3之前版本存在安全漏洞，该漏洞源于守护进程文件处理中存在检查时间与使用时间竞争条件，可能导致攻击者通过符号链接替换父目录组件将文件写入重定向到预期目录之外。具有模块路径写入权限的攻击者可利用此竞争条件创建或覆盖任意文件，当守护进程以高权限运行时可能修改敏感系统文件并实现权限提升。
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-2026-29518

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 9246 chars
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Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
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III. Intelligence Information for CVE-2026-29518

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Patches & Fixes for CVE-2026-29518 (1)

Vendor Advisories for CVE-2026-29518 (1)

Vendor Pages for CVE-2026-29518 (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-2026-43620 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-2026-43617 4.8 MEDIUM Rsync < 3.4.3 Authorization Bypass via Hostname Resolution
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-367

V. Comments for CVE-2026-29518

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