SSHFS versions prior to 3.7.6 are vulnerable to improper link resolution before file access (CWE-59). A malicious SFTP server can return absolute or relative symlink targets containing parent-directory components. SSHFS passes these targets to FUSE for resolution by the client kernel against the local filesystem. The existing mitigation, transform_symlinks, does not process relative targets correctly because transform_symlink() returns early, while sshfs_readlink() copies the server-supplied link target directly to the kernel. This flaw allows a victim or victim-side tool following such symlinks to disclose readable local files to the server or write server-controlled content to writable local files, potentially including critical files like startup or scheduled-task files. The vulnerability is addressed in sshfs version 3.7.6.

An attacker controlling a rogue SFTP server can exploit this vulnerability to cause the sshfs client to follow symlinks that resolve to local filesystem paths. This can lead to unauthorized disclosure of local files or unauthorized modification of writable local files on the client side. The impact includes potential exposure of sensitive information and alteration of critical files such as startup or scheduled-task files, which could lead to further compromise. The CVSS v3.1 score is 9.3 (critical) with high confidentiality and integrity impact, no availability impact, and requires no privileges but user interaction.

This vulnerability is fixed in sshfs version 3.7.6. Users should upgrade to version 3.7.6 or later to remediate this issue. No other official mitigation or temporary fix is documented. Until upgrading, users should avoid mounting filesystems from untrusted or potentially malicious SFTP servers to prevent exploitation.