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 or directly via email to aws-security@amazon.com. Please do not create a public GitHub issue.