Esbuild is a blazing fast JavaScript bundler and minifier, and versions 0.1.6 and 0.1.5 showcase its rapid development pace. Both versions share the same core functionality and license (MIT), packing and shrinking JavaScript code with impressive speed. The description and repository information are identical, confirming that these are incremental releases within the same project. Even the fileCount and unpackedSize in the dist object remain the same as of this version showing that the codebase size impact is negligible, also the tarball url differs because it is a different package.
The most notable distinction between versions 0.1.5 and 0.1.6 lies in their release dates. Version 0.1.6 was released on April 16, 2020, just hours after version 0.1.5, which was released on April 15, 2020. This short timeframe strongly suggests that version 0.1.6 likely addresses a bug fix, a minor enhancement, or a hotfix discovered shortly after the release of 0.1.5.
For developers considering esbuild, this highlights the project's active maintenance and responsiveness to issues. Although the specific changes between these versions aren't detailed in the provided data, the quick turnaround suggests a commitment to stability and quality. When adopting esbuild, checking the changelog or release notes associated with these versions (available on the esbuild GitHub repository) would reveal the precise nature of the update and its potential impact on your project. This rapid iteration is a positive sign, indicating that the developers are dedicated to refining and improving the tool.
All the vulnerabilities related to the version 0.1.6 of the package
esbuild enables any website to send any requests to the development server and read the response
esbuild allows any websites to send any request to the development server and read the response due to default CORS settings.
esbuild sets Access-Control-Allow-Origin: * header to all requests, including the SSE connection, which allows any websites to send any request to the development server and read the response.
https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L121 https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L363
Attack scenario:
http://malicious.example.com).fetch('http://127.0.0.1:8000/main.js') request by JS in that malicious web page. This request is normally blocked by same-origin policy, but that's not the case for the reasons above.http://127.0.0.1:8000/main.js.In this scenario, I assumed that the attacker knows the URL of the bundle output file name. But the attacker can also get that information by
/index.html: normally you have a script tag here/assets: it's common to have a assets directory when you have JS files and CSS files in a different directory and the directory listing feature tells the attacker the list of files/esbuild SSE endpoint: the SSE endpoint sends the URL path of the changed files when the file is changed (new EventSource('/esbuild').addEventListener('change', e => console.log(e.type, e.data)))The scenario above fetches the compiled content, but if the victim has the source map option enabled, the attacker can also get the non-compiled content by fetching the source map file.
npm inpm run watchfetch('http://127.0.0.1:8000/app.js').then(r => r.text()).then(content => console.log(content)) in a different website's dev tools.Users using the serve feature may get the source code stolen by malicious websites.