GHSA-44vr-rwwj-p88h Shescape vulnerable to insufficient escaping of whitespace

• npm shescape: >= 1.4.0, < 1.5.8 → fixed in 1.5.8

Impact This only impacts users that use the `escape` or `escapeAll` functions with the `interpolation` option set to `true`. Example: ```javascript import cp from "node:child_process"; import * as shescape from "shescape"; // 1. Prerequisites const options = { shell: "bash", // Or shell: "dash", // Or shell: "powershell.exe", // Or shell: "zsh", // Or shell: undefined, // Only if the default shell is one of the affected shells. }; // 2. Attack (one of multiple) const payload = "foo #bar"; // 3. Usage let escapedPayload; shescape.escape(payload, { interpolation: true }); // Or shescape.escapeAll(payload, { interpolation: true }); cp.execSync(`echo Hello ${escapedPayload}!`, options); // _Output depends on the shell being used_ ``` 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. • Affected shells: _Bash_, _Dash_, _Zsh_, _PowerShell_ 2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters. • Affected shells: _Bash_ 3. Invoke arbitrary commands by inserting a line feed character. • Affected Shells: _Bash_, _Dash_, _Zsh_, _PowerShell_ 3. Invoke arbitrary commands by inserting a carriage return character. • Affected Shells: _PowerShell_ Patches 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. Workarounds 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, you can 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. References • https://github.com/ericcornelissen/shescape/pull/322 • https://github.com/ericcornelissen/shescape/pull/324 • https://github.com/ericcornelissen/shescape/pull/332 • https://github.com/ericcornelissen/shescape/releases/tag/v1.5.7 • https://github.com/ericcornelissen/shescape/releases/tag/v1.5.8 For more information • Comment on: • For behaviour 1 (PowerShell): https://github.com/ericcornelissen/shescape/pull/322 • For behaviour 1 (Bash, Dash, Zsh): https://github.com/ericcornelissen/shescape/pull/324 • For behaviour 2, 3, 4 (_any shell_): https://github.com/ericcornelissen/shescape/pull/332 • Open an issue at https://github.com/ericcornelissen/shescape/issues (_New issue_ > _Question_ > _Get started_) • If you're missing CMD from this advisory, see https://github.com/ericcornelissen/shescape/security/advisories/GHSA-jjc5-fp7p-6f8w [v1.5.7]: https://github.com/ericcornelissen/shescape/releases/tag/v1.5.7 [v1.5.8]: https://github.com/ericcornelissen/shescape/releases/tag/v1.5.8