Esbuild version 0.12.7 is a minor release following version 0.12.6 of this blazing-fast JavaScript bundler and minifier, designed for developers who demand performance. Both versions share the same MIT license and originate from the same GitHub repository, ensuring consistent quality and community support. The core functionality remains consistent, focusing on rapid build times to enhance the development workflow.
The key difference lies in subtle refinements and potential bug fixes implemented in version 0.12.7. While the file count remains the same at 6, the unpacked size sees a marginal increase of 1 byte, suggesting minor code adjustments or optimizations. The release date of 0.12.7 is June 8, 2021, subsequent to the June 4, 2021 release of version 0.12.6.
For developers, this suggests that upgrading to 0.12.7 is likely a low-risk operation and could potentially introduce performance improvements or address niche edge-case scenarios. Esbuild’s primary benefit remains its exceptional speed in bundling and minifying JavaScript, making it an attractive choice for projects of all sizes. This speed translates to faster development cycles and improved website performance. Keep an eye on the official esbuild GitHub repository for detailed changelogs to understand the specific nuances between these versions and determine if the changes impact your particular use case. Regardless, esbuild empowers Javascript developers to build apps better and faster!
All the vulnerabilities related to the version 0.12.7 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.