Esbuild versions 0.12.1 and 0.12.2 are both iterations of an extremely fast JavaScript bundler and minifier, licensed under MIT. Both versions share the same core characteristics: a compact distribution structure consisting of 6 files and an unpacked size of 88232 bytes. Developers considering esbuild for their projects will appreciate its speed and efficiency in bundling and minifying JavaScript code, making it a valuable asset for optimizing web application performance.
The key difference lies in their release dates. Version 0.12.2 was released on May 25, 2021, while version 0.12.1 was released on May 19, 2021, indicating a roughly six-day gap between releases. While the provided data doesn't explicitly detail the specific changes or bug fixes included in the 0.12.2 update, the rapid succession suggests that it likely incorporates minor enhancements, bug fixes, or performance tweaks compared to its predecessor. Developers should consult the esbuild changelog or release notes on the official GitHub repository to get a more granular understanding of the modifications introduced in version 0.12.2 and determine if upgrading from 0.12.1 is beneficial for their specific use case. Checking the changelog allows developers to make a correct decision selecting the best version for their project.
All the vulnerabilities related to the version 0.12.2 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.