Esbuild version 0.14.20 represents a minor update over its predecessor, version 0.14.19, within the fast JavaScript and CSS bundler ecosystem. Both versions share the core functionality of providing extremely fast bundling and minification, targeting developers seeking performance optimization in their build processes. The essential library description remains consistent: "An extremely fast JavaScript and CSS bundler and minifier."
The most apparent change lies in the version numbers of the platform-specific dependencies. Both the dependencies and optionalDependencies sections show an increment from "0.14.19" to "0.14.20" for packages like esbuild-linux-64, esbuild-darwin-arm64, and others covering various operating systems and architectures. This indicates that the core esbuild package and its associated platform binaries have been updated, likely containing bug fixes, performance enhancements, or compatibility improvements specific to those platforms.
Developers considering an upgrade from 0.14.19 to 0.14.20 should primarily expect subtle improvements, rather than significant feature additions. While the release notes (not provided here) would give specifics, version bumps often address edge cases and improve stability. Given the identical fileCount and unpackedSize in the dist property for both versions (6 files and 115613 unpacked size), the changes introduced between the two are likely minor and focused on refinements rather than structural overhauls of the esbuild library. The release date difference indicates that the newer version includes more recent changes.
All the vulnerabilities related to the version 0.14.20 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.