Esbuild versions 0.11.7 and 0.11.6 are both iterations of the incredibly fast JavaScript bundler and minifier, designed to optimize web development workflows. Both versions share fundamental characteristics: they are licensed under the MIT license, ensuring broad usability; they stem from the same GitHub repository maintained by Evan Wallace, guaranteeing consistent development lineage. Both versions also exhibit identical unpacked sizes and file counts (81483 bytes, 6 files), meaning code size and number of files are the same.
The key distinction lies within their release dates. Version 0.11.7 arrived on April 10, 2021, succeeding version 0.11.6, which was released a few days prior on April 7, 2021. For developers, this subtle difference signifies bug fixes, minor feature enhancements, or performance tweaks incorporated in the newer release. The minimal gap suggests incremental improvements rather than radical changes.
Therefore, developers seeking the most up-to-date and potentially refined experience should opt for version 0.11.7. While the core functionality remains consistent, sticking with the latest version often provides the most stable and optimized build process. If already on 0.11.6, an upgrade is advisable, especially if encountering issues potentially addressed by the small refinements to the code of the latter version. Both versions maintain esbuild's promise of blazing-fast builds, which is the main draw.
All the vulnerabilities related to the version 0.11.7 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.