Insufficient escaping of whitespace in shescape

Summary

Shescape is a simple shell escape package for JavaScript. Affected versions were found to have insufficient escaping of white space when interpolating output. This issue only impacts users that use the `escape` or `escapeAll` functions with the `interpolation` option set to `true`. The result is that if an attacker is able to include whitespace in their input they can: 1. Invoke shell-specific behaviour through shell-specific special characters inserted directly after whitespace. 2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters. 3. Invoke arbitrary commands by inserting a line feed character. 4. Invoke arbitrary commands by inserting a carriage return character. Behaviour number 1 has been patched in [v1.5.7] which you can upgrade to now. No further changes are required. Behaviour number 2, 3, and 4 have been patched in [v1.5.8] which you can upgrade to now. No further changes are required. The best workaround is to avoid having to use the `interpolation: true` option - in most cases using an alternative is possible, see the recipes for recommendations. Alternatively, users may strip all whitespace from user input. Note that this is error prone, for example: for PowerShell this requires stripping `'\u0085'` which is not included in JavaScript's definition of `\s` for Regular Expressions.

Timeline

1. Aug 1, 2022, 7:15 PM UTCCVE published
2. Apr 22, 2025, 3:37 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: yes · Technical impact: total

3. Apr 22, 2025, 5:46 PM UTCRecord last updated

Affected versions

• ericcornelissen shescape

  >=1.4.0 < 1.5.8

• shescapenpm

  From 1.4.0 · fixed in 1.5.8

References 5