Esbuild versions 0.5.16 and 0.5.17 are both iterations of the exceptionally fast JavaScript bundler and minifier. They share a common foundation, boasting the same core description, MIT license, and repository details, indicating a continuing commitment to open-source principles and community collaboration. Both versions also demonstrate the same file structure and unpacked size, suggesting underlying architectural similarities in terms of the included files and overall footprint.
The key difference lies in their release dates. Version 0.5.17 was released on July 2nd, 2020, while version 0.5.16 was released on June 30th, 2020, just a couple of days before. From a developer's perspective, this points to a rapid development cycle and a dedication to providing frequent updates. While the provided metadata doesn't detail the specific changes or fixes included in version 0.5.17, the proximity of the releases strongly suggests that it likely contains bug fixes, performance improvements, or minor feature enhancements addressing issues identified in the preceding version.
Developers using esbuild should therefore consider upgrading to version 0.5.17 to benefit from any stability improvements and potential new optimizations. Checking the official esbuild changelog or release notes accompanying version 0.5.17 would reveal the specific modifications included and help developers determine if the update addresses particular concerns or unlocks beneficial new capabilities for their projects. This continuous evolution showcases the project's agility and commitment to providing a cutting-edge bundling solution for the JavaScript ecosystem.
All the vulnerabilities related to the version 0.5.17 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.