Esbuild version 0.14.48 represents a minor update over the previous stable version, 0.14.47, primarily focusing on internal dependency updates. Both versions share the same core functionality as an extremely fast JavaScript and CSS bundler and minifier, boasting exceptional performance compared to other similar tools. The key difference lies in the versioning of their platform-specific dependencies. Both versions ship with a comprehensive set of pre-built binaries for various operating systems and architectures, ensuring compatibility across diverse development environments. These include specific builds for Linux (32-bit, 64-bit, ARM, ARM64, s390x, ppc64le, riscv64, mips64le), macOS(64-bit, ARM64), Windows (32-bit, 64-bit, ARM64), Android (64-bit, ARM64), FreeBSD (64-bit, ARM64), NetBSD (64-bit), SunOS (64-bit), and OpenBSD (64-bit). While the core esbuild package lists these binaries as both dependencies and optional dependencies, this structure allows npm to install the appropriate pre-built binary for your system, enhancing the installation process. For developers, the choice between 0.14.47 and 0.14.48 hinges on the need for the latest dependency patches. Generally, upgrading to the latest minor version is recommended for stability and potential bug fixes, although the functional differences between these two versions are minimal. Both are released under the MIT license and are available on the npm registry and GitHub. A minor increase of unpacked size with 53 bytes can also be observed.
All the vulnerabilities related to the version 0.14.48 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.