Esbuild version 0.8.54 represents a minor version update to the blazing-fast JavaScript bundler and minifier, succeeding version 0.8.53. Both versions maintain the core promise of esbuild: delivering unparalleled build speeds for modern web development workflows. Key features like highly optimized minification, tree shaking, and support for various JavaScript and TypeScript syntax remain consistent across both releases. The license continues to be MIT, ensuring flexibility and broad compatibility for developers.
While the fundamental functionality and architecture remain the same (indicated by the identical fileCount and unpackedSize in the dist object), the primary distinction lies in the release date. Version 0.8.54 was published on March 1, 2021, a few days after version 0.8.53, which was released on February 27, 2021. This suggests that version 0.8.54 likely includes bug fixes, performance tweaks, or minor enhancements built upon the foundation of 0.8.53. Although specific changes aren't detailed in the provided data, developers looking for the most recent stable build should opt for version 0.8.54. This ensures they benefit from any recent improvements and resolutions that address potential issues present in the preceding version. For projects already using esbuild, upgrading from 0.8.53 to 0.8.54 should be a straightforward process, given the similar structural footprint. Consider consulting the official esbuild changelog for a comprehensive list of specific modifications.
All the vulnerabilities related to the version 0.8.54 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.