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:
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
For more information
If you have any questions or comments about this advisory:
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: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
For more information
If you have any questions or comments about this advisory: