GHSA-jjc5-fp7p-6f8w Shescape prior to 1.5.8 vulnerable to insufficient escaping of line feeds for CMD

• npm shescape: < 1.5.8 → fixed in 1.5.8

Impact This impacts users that use Shescape (any API function) to escape arguments for cmd.exe on Windows. An attacker can omit all arguments following their input by including a line feed character (`'\n'`) in the payload. Example: ```javascript import cp from "node:child_process"; import * as shescape from "shescape"; // 1. Prerequisites const options = { shell: "cmd.exe", }; // 2. Attack const payload = "attacker\n"; // 3. Usage let escapedPayload; escapedPayload = shescape.escape(payload, options); // Or escapedPayload = shescape.escapeAll([payload], options)[0]; // Or escapedPayload = shescape.quote(payload, options); // Or escapedPayload = shescape.quoteAll([payload], options)[0]; cp.execSync(`echo Hello ${escapedPayload}! How are you doing?`, options); // Outputs: "Hello attacker" ``` > Note: `execSync` is just illustrative here, all of `exec`, `execFile`, `execFileSync`, `fork`, `spawn`, and `spawnSync` can be attacked using a line feed character if CMD is the shell being used. Patches This bug has been patched in [v1.5.8] which you can upgrade to now. No further changes are required. Workarounds Alternatively, line feed characters (`'\n'`) can be stripped out manually or the user input can be made the last argument (this only limits the impact). References • https://github.com/ericcornelissen/shescape/pull/332 • https://github.com/ericcornelissen/shescape/releases/tag/v1.5.8 For more information If you have any questions or comments about this advisory: • Comment on https://github.com/ericcornelissen/shescape/pull/332 • Open an issue at https://github.com/ericcornelissen/shescape/issues (_New issue_ > _Question_ > _Get started_) [v1.5.8]: https://github.com/ericcornelissen/shescape/releases/tag/v1.5.8