Esbuild 0.19.0 represents a subtle yet significant update over version 0.18.20, continuing its evolution as a leading JavaScript and CSS bundler. While the core description remains consistent – an "extremely fast" bundler and minifier – the internal changes are noteworthy for developers prioritizing performance and compatibility.
Notably, both versions share a similar dependency structure, with identical lists of dependencies and optional dependencies targeting various operating systems and architectures: Linux (arm, x64, ia32, arm64, ppc64, s390x, loong64, riscv64, mips64el), Windows (x64, ia32, arm64), macOS (x64, arm64), Android (arm, x64, arm64), FreeBSD (x64, arm64), NetBSD (x64), SunOS (x64), and OpenBSD (x64). This extensive support underscores esbuild's commitment to cross-platform compatibility. The dependencies' version numbers were also updated in version 0.19.0
A key difference lies in the release date. Version 0.19.0 was released just hours after 0.18.20. The unpackedSize of the tarball changed slightly, from 131272 in 0.18.20 to 131240 in 0.19.0. These small changes often signify bug fixes, performance tweaks, or minor feature additions. Developers upgrading should review the official esbuild changelog on GitHub for a comprehensive list of changes. By keeping its support of various architectures and OS, Esbuild makes sure developers can use it in all kind of environments and benefit from it's bundling capabilities.
In essence, while both versions offer the core functionality of esbuild, version 0.19.0 likely includes refinements that enhance stability and performance. Developers are encouraged to upgrade to leverage the latest improvements, ensuring an optimal bundling experience.
All the vulnerabilities related to the version 0.19.0 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.