CVE-2026-53802 in rsync
Summary
by MITRE • 08/13/2026
rsync before 3.5.0 contains an arbitrary file read vulnerability that allows attackers to read files accessible to the rsync daemon process by exploiting symlink following in input configuration file handling including --files-from, --password-file, and filter merge files. Attackers can place a symlink at a predictable --files-from or --password-file path, or supply a --files-from path that escapes the daemon module root, to read arbitrary files accessible to the rsync process.
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Analysis
by VulDB Data Team • 08/22/2026
The rsync vulnerability present in versions prior to 3.5.0 represents a critical arbitrary file read flaw that fundamentally undermines the security model of the rsync daemon process. This vulnerability stems from improper handling of symbolic links within input configuration files, specifically affecting parameters such as --files-from, --password-file, and filter merge files. The flaw allows attackers to manipulate file access patterns through symlink exploitation, creating a pathway for unauthorized data exfiltration that directly compromises the integrity and confidentiality of remote file synchronization operations.
The technical implementation of this vulnerability exploits the daemon's failure to properly validate symbolic link paths during configuration file processing. When rsync processes input files containing symlinks, it follows these links without adequate path validation or sandboxing measures, enabling attackers to craft malicious symlink structures that point to sensitive system files accessible to the rsync process. This behavior creates a privilege escalation scenario where unprivileged users can gain access to files that would normally be restricted by file permissions and directory boundaries. The vulnerability manifests particularly when attackers can predict or control the paths used by --files-from or --password-file parameters, allowing them to bypass normal access controls through symlink manipulation.
From an operational impact perspective, this vulnerability poses significant risks to organizations relying on rsync for file synchronization across networked environments. Attackers can leverage this flaw to read configuration files, authentication credentials, system logs, and other sensitive data accessible to the rsync daemon process. The attack vector extends beyond simple file reading to potentially include privilege escalation scenarios where attackers might access files with elevated permissions or extract information that could facilitate further attacks. The vulnerability affects both local and remote exploitation scenarios, making it particularly dangerous in environments where rsync daemons are exposed to untrusted networks or users.
Security practitioners should implement immediate mitigations including upgrading to rsync version 3.5.0 or later, which includes proper symlink validation and path resolution controls. Organizations must also review their rsync daemon configurations to ensure that file access restrictions are properly enforced and that input parameters are validated against predictable attack patterns. The vulnerability aligns with CWE-59 and CWE-22 categories related to improper link resolution and path traversal issues, while also mapping to ATT&CK techniques involving privilege escalation through file system manipulation. Additional defensive measures should include network segmentation of rsync services, implementation of strict access controls for configuration files, and regular monitoring for suspicious symlink creation patterns in rsync-related directories.
The remediation approach requires comprehensive system hardening including proper input validation for all rsync parameters, enforcement of strict path resolution policies, and implementation of automated monitoring for potential symlink-based attacks. Organizations should also consider implementing additional security controls such as file integrity monitoring, privileged access management, and regular security assessments of their rsync configurations to prevent exploitation of similar vulnerabilities in other components of their file synchronization infrastructure.