Esbuild is a blazing-fast JavaScript bundler and minifier, and versions 0.11.0 and 0.11.1 represent incremental improvements in this already impressive tool. Both versions maintain the core functionality of bundling and minifying JavaScript with exceptional speed. They share identical descriptions, license, and repository information, highlighting their shared lineage and commitment to open-source principles under the MIT license.
A key observation is that even with a minor version bump, the file count and unpacked size between the two versions remain the same. This suggests that the changes introduced in 0.11.1 were likely bug fixes, performance enhancements, or internal refactoring rather than the addition of new features that would significantly impact the package size.
The most notable difference is the release date. Version 0.11.0 was released on March 29, 2021, at 02:56:16 UTC, while version 0.11.1 followed later the same day, at 23:48:47 UTC. This close proximity in release times suggests that a critical issue was identified in 0.11.0, prompting a quick fix and subsequent release of 0.11.1.
For developers, this means that while both versions provide excellent bundling capabilities, it is highly recommended to use version 0.11.1. The rapid release cycle indicates that it addresses a potential problem present in 0.11.0, making it the more stable and reliable choice for production environments. Always prioritizing the latest stable version ensures you benefit from the most up-to-date optimizations and bug fixes.
All the vulnerabilities related to the version 0.11.1 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.