Esno, a utility for running TypeScript and JavaScript Node.js applications powered by esbuild, saw a significant update moving from version 0.11.0 to 0.12.0. Developers considering upgrading or choosing a version should note key changes in dependencies. The newer version upgrades esbuild from ^0.13.3 to ^0.13.12, potentially incorporating performance improvements and bug fixes from the esbuild project. esbuild-register also sees an upgrade from ^3.0.0 to ^3.1.0, likely addressing improvements in the on-the-fly compilation process of TypeScript. Similarly, esbuild-node-loader jumps from ^0.5.0 to ^0.6.0, suggesting enhancements in how esbuild handles module loading within Node.js.
A notable addition in version 0.12.0 is the inclusion of import-meta-resolve at version ^1.1.1, which provides standardized way to resolve module specifiers from import.meta.url. This addition is beneficial where dynamic module resolution is needed. Furthermore, version 0.12.0 introduces typescript as a dev dependency at version ^4.4.4. This provides a better development experience for projects leveraging TypeScript. While both versions share common dev dependencies like zx and fsxx, developers should evaluate the impact of dependency updates on compatibility and performance within their specific projects. The release of version 0.12.0 happened on "2021-11-09T06:43:33.173Z", just a few days after the v0.11.0 ("2021-11-03T03:31:59.489Z").
All the vulnerabilities related to the version 0.12.0 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.