Esbuild versions 0.8.34 and 0.8.35 represent incremental updates to this exceptionally fast JavaScript bundler and minifier. Both versions maintain the core promise of esbuild: delivering unparalleled build speeds alongside efficient minification, crucial for modern web development workflows. Key features like support for various module formats (ESM, CommonJS), tree shaking, and code splitting are consistent across both releases.
The primary difference lies in the release dates, with version 0.8.35 being published on January 26, 2021, and version 0.8.34 on January 21, 2021. While information on specific bug fixes or new features included in 0.8.35 compared to 0.8.34 isn't provided in these metadata snippets, the quick release suggests possible refinements or critical patches quickly addressed after the 0.8.34 release.
For developers, esbuild offers a compelling alternative to slower bundlers. Its speed significantly reduces build times, accelerating development cycles and improving developer productivity. Whether you're building a small website or a large application, esbuild can drastically improve your build performance. If you are already using esbuild, upgrading to the latest minor version, 0.8.35, is recommended to capitalize on potential fixes and optimizations, ensuring more stable and reliable builds. Always test new versions in a non-production environment first, nonetheless.
All the vulnerabilities related to the version 0.8.35 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.