Exposure of home directory through shescape on Unix with Bash

Impact

The issue allows for exposure of the home directory on Unix systems when using Bash with the escape or escapeAll functions from the shescape API with the interpolation option set to true. Other tested shells, Dash and Zsh, are not affected.

const cp = require("child_process");
const shescape = require("shescape");

const payload = "home_directory=~";
const options = { interpolation: true };
console.log(cp.execSync(`echo ${shescape.escape(payload, options)}`));
// home_directory=/home/user

Depending on how the output of shescape is used, directory traversal may be possible in the application using shescape.

Patches

The issue was patched in v1.5.1.

Workarounds

Manually escape all instances of the tilde character (~) using arg.replace(/~/g, "\\~").

References

See GitHub issue https://github.com/ericcornelissen/shescape/issues/169.