Esbuild is an extremely fast JavaScript and CSS bundler and minifier, and delving into the version differences between 0.14.38 and 0.14.39 reveals subtle yet crucial enhancements. Both versions maintain the same core description, MIT license, and repository details, reaffirming the project's stability and commitment to open-source principles. However, the key differentiator lies in the versioning of their dependencies.
Both versions list an extensive array of platform-specific dependencies like esbuild-linux-64, esbuild-darwin-arm64, and esbuild-windows-64, each tailored to different operating systems and architectures. The newer version, 0.14.39, updates all these platform-specific dependencies to their corresponding "0.14.39" versions, while the older version uses "0.14.38". While no specific feature additions are mentioned, this dependency update implies improvements under the hood, potentially encompassing bug fixes, performance optimizations specific to those platforms, or enhanced compatibility with the respective operating systems.
The release date further illuminates the update timeline, with 0.14.39 released roughly three weeks after 0.14.38. Developers should consider upgrading to the newer version (0.14.39) to benefit from the consolidated improvements embedded within these platform-specific dependency updates. Although the fileCount and unpackedSize remain the same, meaning that no additional features are added, these small improvements can translate into greater efficiency of the build and the stability of the final app, since the package is well maintained according to the quick release of the new patch.
All the vulnerabilities related to the version 0.14.39 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.