Esbuild version 0.12.13 is a minor update to the extremely fast JavaScript bundler and minifier, following closely after version 0.12.12. Both versions maintain the core functionality of bundling and minifying JavaScript, Typescript and JSX codebases for faster web applications. Licensing remains under the MIT license, ensuring broad usability for developers. Both packages have the same amount of files of 6, but 0.12.13 increases in size of only 245 bytes, incrementing from 88455 to 88700 unpacked bytes.
From a developer's perspective, while the description remains the same, one can still expect incremental improvements in performance, bug fixes, and potentially new feature enhancements. Given the small change in unpacked size and the quick release cycle, the differences are likely focused on stability, performance optimization or resolving specific edge cases. Developers should always consult the official changelog or release notes (typically available on the esbuild GitHub repository) for a detailed breakdown of changes between these two versions and to assess if the updates are relevant to their specific project requirements. Upgrading from 0.12.12 to 0.12.13 is recommended to benefit from the latest stability and performance improvements. The release date of 2021-07-01T06:21:45.490Z (0.12.13) compared to 2021-06-28T23:00:23.638Z (0.12.12) indicates a very recent update, suggesting addressing immediate concerns or refinements.
All the vulnerabilities related to the version 0.12.13 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.