Esbuild is a blazing-fast JavaScript bundler and minifier, offering a streamlined development workflow for modern web projects. Examining versions 0.4.14 and 0.4.13, the core functionality remains consistent, continuing to provide developers with unparalleled build speeds compared to traditional bundlers. Both versions share the same MIT license, ensuring freedom and flexibility in usage, and are sourced from the official GitHub repository. Crucially, the file count and unpacked size of the packages are identical, hinting at incremental improvements rather than significant architectural changes between the releases.
What distinguishes version 0.4.14 is its release date of June 11, 2020, a mere two days after version 0.4.13. This suggests that the changes likely address either bug fixes, performance tweaks or very specific edge cases encountered by early adopters. Developers upgrading from 0.4.13 to 0.4.14 should anticipate subtle enhancements in build performance or resolution process rather than drastic shifts in API behavior. The dist details of both releases are standard, including a standard tgz distribution, to easy access to all components
For those seeking maximum stability and the latest refinements, upgrading to 0.4.14 offers a modest yet potentially beneficial update, keeping projects at the cutting edge of esbuild's continuous evolution. It's always good to check the project’s official changelog and release notes for specifics.
All the vulnerabilities related to the version 0.4.14 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.