SSHFS Symlink Escape: Rogue SFTP Server → Local File Read/Write
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 3.7.6
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: no
- Technical impact: total
Summary
SSHFS is a network filesystem client for connecting to SSH servers. Prior to version 3.7.6, a rogue SFTP server can return absolute symlink targets or relative targets containing parent-directory components that SSHFS passes through FUSE for resolution by the client kernel against the local filesystem. The documented transform_symlinks mitigation does not contain relative targets because transform_symlink() returns early at sshfs.c:2181, while sshfs_readlink() at sshfs.c:2234 to sshfs.c:2236 otherwise copies the server-supplied link target to the kernel. A victim or victim-side tool that follows such a link through ordinary operations such as cp, rsync, backup tooling, or an editor can disclose readable local files back to the server or write server-controlled content to writable local files, potentially including startup or scheduled-task files. This issue is fixed in version 3.7.6.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: poc · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- libfuse sshfs
fixed in 3.7.6