Esbuild version 0.7.8 introduces incremental improvements over its predecessor, version 0.7.7, in its core functionality as an extremely fast JavaScript bundler and minifier. Both versions share the same MIT license and repository location on GitHub, underscoring a commitment to open-source principles.
While the fundamental description remains unchanged, subtle differences exist in the unpacked size of the distributed tarball, with version 0.7.8 being marginally larger at 38158 bytes compared to 0.7.7's 38150 bytes, suggesting minor code or build process refinements. Of course, both share the same amount of files.
A key difference lies in the release date, with version 0.7.8 published on September 29, 2020, a slight release of two days after version 0.7.7, which was released on September 27, 2020. For developers, this quick update cycle signals active maintenance and bug fixes. While the specific nature of the changes between these versions isn't explicitly detailed in the metadata, users can anticipate general improvements to performance, stability, or feature refinement for bundling and minifying JavaScript, TypeScript, and other web assets. The swift release cadence promotes confidence in the tool's reliability and responsiveness to community needs. Developers should always check the official esbuild changelog for detailed update notes.
All the vulnerabilities related to the version 0.7.8 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.