Esbuild version 0.14.9 is a minor update to the blazing-fast JavaScript and CSS bundler, following closely on the heels of version 0.14.8. Both versions maintain the same core functionality and description, focusing on speed and efficiency in bundling and minifying web assets. The key difference lies in the updated dependency versions. While both versions list identical dependencies and optional dependencies, such as esbuild-linux-64, esbuild-windows-64 etc. all are bumped from version 0.14.8 to 0.14.9.
For developers, this means a likely improvement in stability, and potential bug fixes related to specific operating system or architecture targets addressed within those dependency updates. The "releaseDate" field shows that version 0.14.9 was released roughly six days after 0.14.8, suggesting a rapid response to any issues discovered in the earlier release. The unpacked size also sees a very minor change from 108210 to 108396.
This update emphasizes esbuild's commitment to providing a reliable and performant bundler across a wide range of environments. If you're already using esbuild, upgrading to 0.14.9 is recommended to benefit from these refinements. The consistent dependency structure also suggests a seamless upgrade process. Consider reviewing the esbuild releases or commit history for a detailed account of changes bundled within this patch.
All the vulnerabilities related to the version 0.14.9 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.