Esbuild is a blazingly fast JavaScript bundler and minifier, and versions 0.6.18 and 0.6.19 offer developers powerful tools for optimizing their web development workflows. Both versions share the same core characteristics, boasting identical descriptions, licenses (MIT), repository information, file counts (6), and unpacked sizes (32153). This suggests that the changes between these versions might be subtle, focusing on bug fixes, performance improvements, or minor feature additions that don't significantly alter the library's overall footprint.
The key difference lies in their release dates. Version 0.6.18 was released on August 7th, 2020, while version 0.6.19 followed shortly after on August 10th, 2020. This tight release schedule implies that 0.6.19 likely addresses immediate issues discovered in 0.6.18, such as critical bugs or security vulnerabilities.
For developers, upgrading from 0.6.18 to 0.6.19 is generally recommended. Although the detailed changelog isn't provided here, the quick turnaround between releases strongly suggests that version 0.6.19 provides increased stability and reliability. Always consult the official esbuild repository or npm page for the full changelog to understand the specific changes thoroughly before updating, especially if you are using specific configurations or features. Using the latest stable version helps guarantee optimal performance and minimizes the risk of encountering potential issues.
All the vulnerabilities related to the version 0.6.19 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.