Esbuild 0.15.8 is a patch release following closely on the heels of 0.15.7, both versions deliver on esbuild's promise of being an extremely fast JavaScript and CSS bundler and minifier. The description, license (MIT), and repository details remain consistent between the two versions.
The core difference lies in the version numbers of the dependencies and optional dependencies. Both 0.15.7 and 0.15.8 rely on a suite of platform-specific builds (e.g., esbuild-linux-64, esbuild-windows-64, esbuild-darwin-arm64). The newer version bumps these dependencies to their respective "0.15.8" counterparts. This means updates to the core esbuild library likely included targeted fixes or optimizations for specific operating systems and architectures.
Importantly. the file count in the dist object is constand at 7 but the unpackedSize is a bit smaller on the 0.15.8 , 117577 compared to unpackedSize":119851 on the previous version. This suggest there has been a optimisation on the new version. 0.15.8 was released on September 18, 2022, a couple of weeks after 0.15.7. Users should upgrade to 0.15.8 to ensure they have the latest bug fixes and performance improvements relevant to their target platform. For developers incorporating esbuild into their workflows, this small update signifies a commitment to maintaining a stable and performant bundler, optimized for diverse environments. The minor version bump suggests the changes are likely non-breaking, offering a seamless upgrade experience.
All the vulnerabilities related to the version 0.15.8 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.