Shescape is a simple shell escape library for JavaScript. Prior to 2.1.14 and 3.0.1, getEscapeFunction in src/internal/unix/dash.js fails to escape ~ after : or = when applications use the escape or escapeAll APIs on Unix with shell set to dash, or with shell set to true when Dash is the default, and interpolate the result into an assignment prefixed to a command. An attacker who controls the input can supply a value such as :~ to disclose the home-directory path and may change the location on which the command operates. This issue is fixed in versions 2.1.14 and 3.0.1.

Affected: npm: shescape

### Impact

This impacts users of Shescape on Unix systems that explicitly configure `shell` to Dash, or `true` when the default shell is Dash, using the `escape` and `escapeAll` APIs in assignments prefixed to a command.

An attacker may be able to obtain the location of the home directory and, depending on how it is used, change the location on which a command operates in unexpected ways.

```javascript import * as cp from "node:child_process"; import { Shescape } from "shescape";

// 1. Prerequisites const options = { shell: "dash", // Or shell: true, // Only if the default shell is Dash };

// 2. Payload const payload = ":~";

// 3. Usage const shescape = new Shescape(options); let escapedPayload;

escapedPayload = shescape.escape(payload); // Or escapedPayload = shescape.escapeAll([payload]);

// And (example) const result = cp.execSync(`V=${escapedPayload}; echo $V`, options);

// 4. Impact console.log(result.toString()); // Outputs ":" followed by the user's home directory ```

### Patches

This bug has been patched in [v2.1.14] and [v3.0.1] which you can upgrade to now.

If you are already using v3 of Shescape, no further changes are required. If you are using v2 of Shescape it is recommended to upgrade as this version reaches end-of-life status on 2026-09-28, follow the [migration guide] to upgrade to v3.

No patches will be released for version of Shescape lower than v2.0.0.

### Workarounds

Alternatively, users of Shescape can 1) refrain from using Da…