UNIX symbolic link following in Wasmtime - #VU155840
Published: October 15, 2026
Vulnerability details
The vulnerability allows a remote user to escape the filesystem sandbox and read and modify external directories accessible to the host process.
The vulnerability exists due to improper symbolic link following in the wasmtime-wasi filesystem implementation when renaming a symbolic link with a trailing slash. A remote user can create a relative symbolic link pointing to an external directory and rename it with a trailing slash to a path inside the sandbox to escape the filesystem sandbox and read and modify external directories accessible to the host process.
Exploitation requires guest write access to a directory within the sandbox. The issue affects macOS and FreeBSD, but not Linux or Windows. Only symbolic links to directories can be used. The supplied CVSS vector indicates that user interaction is required.