CVE-2026-70460 in rsync
Summary
by MITRE • 08/13/2026
rsync 2.3.3 before 3.5.0 contains a path traversal vulnerability that allows a malicious sender to escape the module root by exploiting symlinks within the module file tree when using --partial-dir or --backup-dir options. Attackers with write access to place a symlink under the module root, or who can exploit a pre-existing trusted symlink, can direct file writes to locations outside the intended module root, achieving arbitrary file write relative to the module root parent.
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Analysis
by VulDB Data Team • 08/13/2026
The rsync vulnerability described represents a critical path traversal flaw that fundamentally compromises the security boundaries established by the software's module system. This weakness exists in versions prior to 3.5.0 and specifically targets the interaction between symbolic links and the --partial-dir or --backup-dir command-line options. The vulnerability stems from insufficient validation of symbolic link paths during file operations, allowing attackers to bypass intended directory restrictions through carefully crafted symlink placement within the module's file tree structure.
The technical implementation of this flaw involves the exploitation of symbolic link resolution within rsync's backup and partial file handling mechanisms. When rsync processes files with --partial-dir or --backup-dir options, it creates temporary or backup files in designated directories relative to the module root. However, if a malicious actor can create or manipulate symbolic links within the module directory tree, these links can point to locations outside the intended module scope. The vulnerability manifests when rsync resolves these symbolic links during file creation operations, effectively allowing writes to arbitrary locations that are not constrained by the module's root directory boundaries.
This path traversal vulnerability directly impacts the integrity and confidentiality of systems using vulnerable rsync versions, particularly in environments where multiple users or processes interact with shared module directories. The operational consequences extend beyond simple unauthorized file access, as attackers can potentially overwrite critical system files, inject malicious content into backup operations, or establish persistent access points through strategic placement of symbolic links. The vulnerability is especially dangerous when combined with existing trusted symlinks that may already exist in the module directory structure, as these pre-existing links require no additional attack surface to exploit.
The security implications of this vulnerability align with CWE-22 Path Traversal and can be mapped to ATT&CK technique T1059 Command and Scripting Interpreter for potential abuse through malicious file placement. Organizations should immediately implement mitigation strategies including upgrading to rsync version 3.5.0 or later, restricting write permissions on module root directories to prevent symlink creation, and implementing strict monitoring of symbolic link usage within rsync module contexts. Additionally, administrators should conduct thorough audits of existing rsync configurations to identify and eliminate any pre-existing trusted symlinks that could be exploited, while ensuring proper file system permissions are enforced to minimize the attack surface available to potential adversaries.