Esbuild version 0.14.5 is a minor update to the extremely fast JavaScript and CSS bundler and minifier, building upon the foundation laid by version 0.14.4. The core functionality and purpose remain consistent: providing developers with a blazingly fast tool for bundling and minifying web assets, significantly improving build times compared to traditional bundlers.
The key difference between the two versions lies primarily in the dependency versions. Both versions depend on and optionally depend on a suite of platform-specific esbuild binaries (e.g., esbuild-linux-64, esbuild-darwin-arm64) tailored to different operating systems and architectures. However, version 0.14.5 updates these dependencies to their respective "0.14.5" versions, while version 0.14.4 uses "0.14.4." This signifies crucial bug fixes, potential performance improvements, or compatibility updates within the platform-specific binaries themselves. While the core esbuild API and usage patterns are likely unchanged, upgrading ensures developers benefit from the latest refinements and stability improvements across various target platforms. The fileCount and unpackedSize remains identical, suggesting that core library size haven't suffered major changes. The difference in the release dates will probably be also relevant for some users. For developers, this update emphasizes the importance of keeping dependencies current for optimal performance and reliability, especially within cross-platform build environments.
All the vulnerabilities related to the version 0.14.5 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.