Esbuild 0.17.16 is a minor version update from 0.17.15 of this blazingly fast JavaScript and CSS bundler and minifier, primarily impacting the underlying platform-specific binaries that power its performance. Both versions share the same core description and licensing (MIT), reinforcing their commitment to speed and ease of use. Examining the dependencies and optionalDependencies reveals a comprehensive suite of pre-built binaries tailored for various operating systems and architectures, including Linux (x64, arm, arm64, ia32, 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). The key difference between the two versions lies in the version numbers of these platform-specific dependencies, all moving from 0.17.15 to 0.17.16. This signals that the update primarily involves improvements, bug fixes, or security patches within these binaries, potentially leading to enhanced stability or performance across different environments. For developers, this means a potentially more robust esbuild experience, particularly when deploying to diverse platforms. While the core API and functionality likely remain the same, upgrading to 0.17.16 ensures they are leveraging the latest optimizations and fixes for their target operating system and architecture provided by these underlying dependencies without changing the main package.
All the vulnerabilities related to the version 0.17.16 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.