Esbuild version 0.15.0 represents a minor version update from the previous stable release, 0.14.54. While the core functionality remains consistent, evidenced by the shared description as an "extremely fast JavaScript and CSS bundler and minifier," a key difference lies in the dependency versions. All platform-specific binary dependencies, such as esbuild-linux-64, esbuild-windows-64, and @esbuild/linux-loong64, are bumped from version 0.14.54 to 0.15.0. This suggests that the update primarily incorporates refinements or bug fixes within the pre-compiled binaries that cater to various operating systems and architectures.
For developers, this means a smoother and potentially more efficient bundling experience across different platforms. While the JavaScript API likely remains largely compatible, upgrading to 0.15.0 ensures that they benefit from the latest platform-specific optimizations and patches developed by the esbuild team. The update likely addresses edge cases or improves performance on specific operating systems. Given that both versions share the same license (MIT) and repository, the transition should be seamless for existing users. Developers can anticipate continued high performance and ease of use, along with subtle improvements relevant to their target deployment environments. The release date difference indicates a recent update, emphasizing ongoing maintenance and developer support.
All the vulnerabilities related to the version 0.15.0 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.