Tsup is a zero-config TypeScript bundler powered by esbuild, designed to simplify the process of creating libraries. Version 6.6.2 introduces some subtle but potentially impactful changes compared to version 6.6.1. Both versions share core dependencies like esbuild, rollup, and sucrase, ensuring consistent performance and compatibility.
The key difference lies in the updated tsup version used as a dev dependency. Version 6.6.2 depends on already released tsup@6.6.1 while version 6.6.1 dependended on tsup@6.4.0 version. This indicates internal updates and refinements to the build process without introducing immediate API breaking change. No dependency version changes occurred in dependencies, peerDependencies or devDependencies sections besides the one mentioned.
For developers, this means upgrading from 6.6.1 to 6.6.2 should be relatively seamless. The core functionality remains the same, offering a streamlined bundling experience for TypeScript libraries. The update likely incorporates bug fixes, performance enhancements, and internal improvements, making it a worthwhile upgrade. While the changes might be incremental, staying up-to-date with the latest version ensures access to the most stable and optimized tooling for your TypeScript projects along with the last bugfixes. Both versions maintain consistent peer dependency requirements for postcss, @swc/core, and typescript, so no impact on project's requirements.
All the vulnerabilities related to the version 6.6.2 of the package
tsup DOM Clobbering vulnerability
A DOM Clobbering vulnerability in tsup v8.3.4 allows attackers to execute arbitrary code via a crafted script in the import.meta.url to document.currentScript in cjs_shims.js components
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.