CVE-2026-71311 in Rclone
Summary
by MITRE • 08/06/2026
rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.0, a valid but nondefault FTP filename encoding in backend/ftp/ftp.go can restore raw CR/LF immediately before an attacker-controlled path is interpolated into the line-oriented FTP control channel, and github.com/jlaffaye/ftp formats the argument through textproto.Conn.Cmd without rejecting CR or LF, allowing a filename such as victim CRLF DELE other-secret CRLF NOOP to inject an independent authenticated FTP command when the victim copies or syncs to a more-privileged FTP destination. This issue is fixed in 1.75.0.
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Analysis
by VulDB Data Team • 08/06/2026
The vulnerability in rclone affects versions prior to 1.75.0 and relates to improper handling of filename encoding in the FTP backend implementation. This flaw exists in the backend/ftp/ftp.go file where a specific configuration can cause raw carriage return and line feed characters to be preserved immediately before attacker-controlled paths are interpolated into the FTP control channel. The issue stems from the fact that the github.com/jlaffaye/ftp library formats arguments through textproto.Conn.Cmd without performing adequate validation to reject control characters including CR and LF. This creates a scenario where malicious filenames can be crafted to inject arbitrary FTP commands directly into the control channel, exploiting the line-oriented nature of FTP protocol communications.
The technical exploitation occurs when an attacker constructs a filename containing CRLF sequences that get inserted before and after the path interpolation in the FTP command execution flow. When a victim performs operations like copying or syncing files to a more privileged FTP destination, these specially crafted filenames can trigger independent authenticated FTP commands to be executed with the privileges of the connecting user. The vulnerability specifically impacts the DELE command injection scenario where an attacker-controlled filename such as "victim CRLF DELE other-secret CRLF NOOP" could result in unintended command execution within the FTP session. This represents a classic command injection vulnerability that leverages the protocol's line-based communication model to bypass normal input validation mechanisms.
From an operational perspective, this vulnerability allows for authenticated command injection attacks against FTP servers that rclone interacts with, potentially enabling attackers to execute arbitrary commands on remote systems with the privileges of the connected user account. The impact is particularly severe when victims perform operations with elevated privileges or access to sensitive data repositories, as the injected commands could result in data exfiltration, system compromise, or privilege escalation within the FTP environment. The vulnerability is classified under CWE-77 and aligns with ATT&CK technique T1059.006 for command injection, specifically targeting network protocols through malformed input handling.
The fix implemented in rclone version 1.75.0 addresses this issue by properly sanitizing filenames to prevent the injection of control characters before they are processed by the FTP library. This mitigation ensures that CR and LF characters are either rejected or properly escaped during path interpolation, preventing the unintended command injection that occurred through the FTP control channel. Organizations should immediately upgrade to rclone 1.75.0 or later versions to protect against this vulnerability, as the issue affects all users who interact with FTP servers using rclone's sync and copy operations, particularly in environments where multiple user privileges exist within the same storage infrastructure.