jsii-diff: Command Injection via npm: package argument

## Summary jsii-diff is a command line tool to compare the API differences between two jsii assemblies, and report errors if there are backwards-incompatible changes to the API. An issue exists where specially formatted command line arguments can be used to execute shell commands via this tool. ## Impact jsii-diff supports downloading packages to compare directly from NPM, so that you can compare a proposed candidate version of your jsii package with an already-published version, by passing an argument that looks like `npm:<package-specifier>`. For example: ``` jsii-diff npm:my-package@latest . ``` By injecting a `;` into the `package-specifier` part of that command, jsii-diff can be tricked into running shell commands. For example: ``` jsii-diff "npm:lodash; touch /tmp/123" . ``` This allows anyone that can control the command-line arguments to jsii-diff to run arbitrary commands with the same permissions as the jsii-diff command itself. ## Patches This issue has been addressed in jsii-diff version 1.131.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes. ## Workarounds If you are unable to update, make sure only trusted actors can control the arguments passed to jsii-diff. ## References If you have any questions or comments about this advisory, AWS asks that you contact AWS Security via the [vulnerability reporting page](https://aws.amazon.com/security/vulnerability-reporting) or directly via email to [[email protected]](mailto:[email protected]). Please do not create a public GitHub issue.

Source published

7 Aug 2026 18:15:47 UTC

Source modified

7 Aug 2026 18:41:00 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS_V4 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Publisher rating · HIGH