Esbuild versions 0.8.43 and 0.8.44 represent incremental updates to this blazingly fast JavaScript bundler and minifier, popular among developers seeking optimized build processes. Both versions share the same core characteristics: MIT license, same repository location, concise file count and similar architecture pointing to an efficient and maintainable codebase.
While the descriptions remain identical, focusing on esbuild's speed and core functionality, the subtle differences between both versions becomes particularly important for developers. Version 0.8.44, released on February 11, 2021, exhibits a slightly larger unpacked size (71605 bytes) compared to version 0.8.43 (69656 bytes), which was released on February 8, 2021. This suggests that the 0.8.44 might include bug fixes, performance enhancements, minor feature additions or updated dependencies. Althought minor, this increase in size can reflect on improvements of the library.
For developers, choosing between these versions might depend on their specific needs and risk tolerance. Those prioritizing stability above all else might stick with the older 0.8.43. However, developers looking for the latest refinements and potential performance gains should upgrade to 0.8.44. Checking the official release notes for detailed change logs is recommended to fully understand the specific enhancements included in version 0.8.44. Esbuild helps with creating faster builds, smaller bundles, reducing development time and improving website performance and overall user experience.
All the vulnerabilities related to the version 0.8.44 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.