Esbuild 0.19.11 represents a minor version update over its predecessor, 0.19.10, within the fast JavaScript and CSS bundler ecosystem. Fundamentally, both versions share the same core functionality: providing an extremely fast bundling and minification solution. This speed advantage remains a key selling point for developers seeking efficient build processes. The description remains consistent, highlighting esbuild's ability to significantly reduce build times compared to other bundlers.
Examining the dependencies and optional dependencies reveals a critical, albeit subtle, difference. While both versions list an extensive set of platform-specific packages (e.g., @esbuild/linux-x64, @esbuild/win32-arm64) as both dependencies and optional dependencies, the versions of these packages are bumped up to 0.19.11 in the newer release. This suggests bug fixes or performance improvements targeted towards very specific architetures where it is running, since the core remains the same. The file size unpacked suffers a small change (increased of ~1000 bytes more or less), which makes us thing of the performance enhancements explained before.
For developers, this update likely means a smoother and more reliable experience, particularly on less common operating systems or architectures. The update may adress some specific bugs reported. While the core API and bundling logic remain unchanged, the enhanced platform-specific support ensures broader compatibility and stability. If problems were appearing when running the platform in a specific architecture, it is highly recommended to update to the newer version. If not, and considering the small changes updated, it is not probably a mandatory update and it is safe to skip it in the short term.
All the vulnerabilities related to the version 0.19.11 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.