Esbuild, a blazing-fast JavaScript and CSS bundler, released version 0.14.28, a minor update following version 0.14.27. Primarily, the change lies within the core dependencies. Both versions share the same description, license (MIT), and repository details, highlighting the project's continued commitment to open-source principles. Both packages support a wide spectrum of operating systems and architectures, from Linux (various flavors) and macOS to Windows and even more niche systems like NetBSD, FreeBSD, and OpenBSD. This comprehensive support makes esbuild a versatile choice for developers targeting different environments.
The crucial distinction rests in the version of the platform-specific binary packages that esbuild depends on such as esbuild-linux-64, esbuild-darwin-arm64 and all the other system specific versions. Version 0.14.28 depends on version "0.14.28" of all of it's dependencies, while version 0.14.27 depends on version "0.14.27". This indicates that the update likely includes crucial bug fixes, performance improvements, or potentially security patches within the core esbuild engine itself, tailored for different platforms. The releaseDate differs significantly between the two versions, signifying the time elapsed between updates, which can be important for those monitoring update frequency. Developers should upgrade to version 0.14.28 to leverage the latest enhancements and fixes in this fast and robust bundling tool. The unpackedSize and fileCount remain the same, implying the core architecture wasn't significantly changed between the 2 versions.
All the vulnerabilities related to the version 0.14.28 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.