Elvish vulnerable to remote code execution via the web UI backend

Impact

Elvish's backend for the experimental web UI (started by elvish -web) hosts an endpoint that allows executing the code sent from the web UI.

The backend does not check the origin of requests correctly. As a result, if the user has the web UI backend open and visits a compromised or malicious website, the website can send arbitrary code to the endpoint in localhost.

Patches

All Elvish releases since 0.14.0 no longer include the experimental web UI, although it is still possible for the user to build a version from source that includes it.

The issue can be patched for previous versions by removing the web UI (found in web, pkg/web or pkg/prog/web, depending on the exact version).

Workarounds

Do not use the experimental web UI.

For more information

If you have any questions or comments about this advisory, please email xiaqqaix@gmail.com.