CVE-2026-82264 in Duplicacy
Summary
by MITRE • 08/28/2026
Duplicacy through 3.2.5 contains a path traversal vulnerability in the restore function that fails to validate entry paths deserialized from snapshot files. Attackers can craft malicious snapshot entries with directory traversal sequences to write files outside the restore directory to arbitrary locations accessible by the restoring user.
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Analysis
by VulDB Data Team • 08/28/2026
The software Duplicacy, specifically through version 3.2.5, contains a critical path traversal vulnerability within its file restoration functionality. This security flaw stems from an insufficient validation mechanism when processing entry paths that are deserialized from snapshot files. When users initiate the restore process, the application reads metadata and file lists stored in these snapshots to determine which files to recover and where to place them on the local filesystem. However, the implementation fails to rigorously sanitize or validate the path strings extracted during this serialization-deserialization cycle. This oversight allows for the injection of directory traversal sequences, such as dot-dot-slash characters, into the file paths contained within the snapshot data.
From a technical perspective, the vulnerability exploits how the application constructs local file system targets based on untrusted input derived from external sources. By crafting malicious snapshot files that contain carefully constructed path entries with relative parent directory references, an attacker can manipulate the destination path calculation logic. Instead of writing restored files strictly within the designated restore target directory as intended by the software design, the traversal sequences cause the operating system to resolve paths upwards through the directory hierarchy. This effectively bypasses the sandboxing or containment boundaries established for the restoration operation, leading to arbitrary file writes on the host system.
The operational impact of this vulnerability is significant and varies depending on the privileges under which Duplicacy is executed. If a user restores from a malicious snapshot while running with standard user permissions, an attacker could overwrite configuration files, scripts, or other data within that user's home directory or accessible subdirectories. This can lead to local privilege escalation if writable system binaries or startup scripts are targeted and replaced with malicious code. In scenarios where Duplicacy is run by a privileged account, such as root on Linux or Administrator on Windows, the consequences are far more severe. An attacker could overwrite critical system files, install persistent backdoors, modify security policies, or disrupt service availability by corrupting essential operating system components. This aligns with Common Weakness Enumeration CWE-22, which defines Improper Limitation of a Pathname to a Restricted Directory, and is categorized under the MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter if used for execution, or T1564 for Hidden Files and Directories depending on the specific payload delivered.
Mitigation strategies must address both immediate remediation and long-term defensive coding practices. The primary solution is to upgrade Duplicacy to a version later than 3.2.5 where this vulnerability has been patched with proper input validation and path canonicalization checks before file operations are performed. For environments unable to update immediately, administrators should enforce strict access controls on snapshot storage locations to prevent untrusted parties from uploading or modifying backup metadata files. Additionally, running the application with minimal necessary privileges reduces the blast radius of any potential exploitation. Developers implementing similar restoration features in other software should ensure that all path inputs are resolved to their absolute canonical forms and verified against a whitelist of allowed base directories before proceeding with file system operations. This approach ensures that even if traversal sequences are present in the input, they cannot escape the intended directory structure due to strict boundary enforcement at the application logic level rather than relying solely on operating system protections which may be bypassed by such techniques.