A rogue SFTP server can supply symlink targets with absolute paths or relative paths containing parent-directory components. SSHFS copies these targets to the kernel through FUSE, allowing the client to resolve and follow them. If a legitimate or malicious server returns such a link, an attacker can read any local files that the client can access or overwrite writable files, including startup scripts or scheduled-task files. The flaw originates from the transform_symlinks mitigation not filtering relative targets, and the readlink logic propagating them unchanged.

The vulnerability affects the libfuse SSHFS client up to and including version 3.7.5. Any system running a pre‑3.7.6 build of SSHFS and connecting to an SFTP server may be impacted.

The CVSS score is 9.3, indicating a critical severity. EPSS data is not available, and the vulnerability is not listed in the CISA KEV catalog. The attack vector is remote: a malicious or compromised SFTP server can deliver the exploit over an established SSH connection, requiring no local user interaction other than mounting the filesystem. Because the flaw permits local file read and write, it allows both confidentiality and integrity violations for all files the user can access, potentially leading to full system compromise if the attacker can modify startup or scheduled-task files.