Esbuild version 0.15.5 is a minor release following closely on the heels of version 0.15.4, both iterations of this extremely fast JavaScript and CSS bundler and minifier. Primarily, the upgrade appears to involve updating the dependency versions of the platform-specific binaries such as esbuild-linux-64, esbuild-darwin-arm64 and others across all supported operating systems and architectures. These dependencies are listed in both the dependencies and optionalDependencies sections, ensuring esbuild can leverage the appropriate binary for maximum performance on various platforms.
The releaseDate highlights the rapid iteration, with 0.15.5 released just hours after 0.15.4. This suggests a hotfix or minor update addressing potentially specific issues or optimizations found shortly after the initial 0.15.4 release. For developers, while the core functionality remains consistent, upgrading to 0.15.5 is recommended to benefit from the latest platform-specific optimizations, bug fixes, and potential security patches embedded within the updated binaries.
The file count and unpacked size in the dist object remains identical, indicating no significant structural changes in the package. This makes the upgrade process relatively straightforward, minimizing the risk of compatibility issues. Developers should always review the official esbuild changelog for a detailed breakdown of changes in each release, empowering them to make informed decisions about upgrading and leveraging the latest performance enhancements.
All the vulnerabilities related to the version 0.15.5 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.