Wasmer is a web assembly (wasm) Runtime supporting WASIX, WASI and Emscripten. If the preopened directory has a symlink pointing outside, WASI programs can traverse the symlink and access host filesystem if the caller sets both oflags::creat and rights::fd_write. Programs can also crash the runtime by creating a symlink pointing outside with path_symlink and path_opening the link. This issue has been addressed in commit b9483d022 which has been included in release version 4.3.2. Users are advised to upgrade. There are no known workarounds for this vulnerability.