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Rsync CVE-2026-44509

| EUVDEUVD-2026-46100 MEDIUM
Improper Link Resolution Before File Access (CWE-59)
2026-07-20 GitHub_M
6.3
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
6.3 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
vuln.today AI
6.3 MEDIUM

AV:L and PR:L reflect mandatory local access; AC:H captures race condition timing difficulty; C:H/I:H reflect permission/ownership manipulation on out-of-module files; A:N as no availability impact is described.

3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
4.0 AV:L/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

3
Patch available
Jul 20, 2026 - 23:18 EUVD
Analysis Generated
Jul 20, 2026 - 21:31 vuln.today
CVE Published
Jul 20, 2026 - 20:27 cve.org
MEDIUM 6.3

DescriptionCVE.org

Rsync is a file-copying tool that uses a delta-transfer algorithm to synchronize remote and local files. In versions prior to 3.4.3, previous bug fixes for symlink races in open() calls missed races in other path based system calls like chmod() and chown(). For rsync daemons with "use chroot = no" this allows an attacker with local filesystem access to change permissions, ownership or timestamp on a file outside the exported module. This issue is fixed in version 3.4.3.

AnalysisAI

Rsync daemon versions prior to 3.4.3 expose a symlink race condition (TOCTOU) in path-based system calls - specifically chmod() and chown() - that prior security patches overlooked when fixing analogous races in open(). When deployed with 'use chroot = no', an attacker with local filesystem write access to an exported module directory can redirect these calls through a symlink to files outside the module boundary, altering permissions, ownership, or timestamps on otherwise inaccessible files. No public exploit has been identified at time of analysis, and the issue is addressed in rsync 3.4.3.

Technical ContextAI

Rsync (CPE: cpe:2.3:a:rsyncproject:rsync:*:*:*:*:*:*:*:*) is a widely deployed file synchronization tool using a delta-transfer algorithm for efficient local and remote file copying. CWE-59 (Improper Link Resolution Before File Access, 'Link Following') describes the root cause: path-based system calls such as chmod() and chown() resolve symbolic links at call time, creating a window between rsync's path validation and the actual syscall. When 'use chroot = yes' is active, the daemon is sandboxed to the module root, eliminating the boundary escape. With 'use chroot = no', rsync depends entirely on its own path checks to enforce module boundaries, making it susceptible to this TOCTOU race. Prior developers fixed the same class of race in open() calls but did not address the equivalent exposure in other path-based syscalls, leaving this residual vulnerability.

RemediationAI

Upgrade to rsync 3.4.3, which is the vendor-released patch that closes the symlink race in chmod() and chown() path-based calls. For deployments where immediate upgrade is not feasible, enable 'use chroot = yes' in rsyncd.conf - this sandboxes the daemon to the module root directory, preventing any out-of-module file access regardless of symlink manipulation; note that chroot requires the daemon to run with sufficient privileges to establish the chroot and may restrict certain rsync features or require pre-population of libraries within the module directory. Additionally, tighten local filesystem permissions so that only trusted users have write access to exported module directories, reducing the attacker's ability to plant symlinks. Restrict rsync daemon exposure to trusted internal network segments as a defense-in-depth measure. The advisory is at https://github.com/RsyncProject/rsync/security/advisories/GHSA-4h9m-w5ff-j735.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Micro 5.3 Affected
SUSE Linux Enterprise Micro 5.4 Affected
SUSE Linux Enterprise Micro 5.5 Affected

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CVE-2026-44509 vulnerability details – vuln.today

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