Esbuild is a blazing-fast JavaScript bundler and minifier, designed to significantly accelerate your build processes. Version 0.6.33 builds upon the foundation of version 0.6.32, offering a potentially incremental update for developers already leveraging this tool. One immediate difference is the release date, with version 0.6.33 being published on September 9th, 2020, a mere two days after version 0.6.32, which was released on September 7th, 2020.
While both versions share the same core description, license (MIT), repository details, file count (6), and unpacked size (31228), the short time between releases suggests 0.6.33 likely contains bug fixes, minor performance improvements, or very specific edge-case resolutions not present in 0.6.32. Developers encountering issues with 0.6.32 or seeking the absolute latest refinements should consider upgrading to 0.6.33.
For new users, Esbuild promises remarkably fast bundling and minification, leading to faster development cycles and improved website performance. To use it install via NPM and run it from the command line. While the core functionalities remain consistent between these versions, staying current with the latest release (0.6.33) is generally recommended to benefit from any recent enhancements addressing stability or performance, guaranteeing that the version is up to date and fully operational. Always refer to the official Esbuild changelog for comprehensive information on specific changes within each version.
All the vulnerabilities related to the version 0.6.33 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.