Esbuild version 0.7.20 represents a minor update following version 0.7.19 in this extremely fast JavaScript bundler and minifier. Both versions maintain the same MIT license and originate from the same GitHub repository, ensuring continued open-source access and collaborative development. The core promise of esbuild – speed and efficiency in bundling and minifying JavaScript – remains consistent across both releases.
A subtle difference appears in the dist section, where version 0.7.20 presents a slightly larger unpackedSize of 39872 bytes compared to 0.7.19's 39691 bytes, suggesting internal optimizations or bug fixes that contribute to a marginal increase in size. These likely imply refinement of existing features rather than the introduction of major new capabilities. The releaseDate shows that version 0.7.20 was published on October 25, 2020, just a few days after version 0.7.19, which came out on October 21, 2020.
For developers, deciding between these versions depends on their risk tolerance and need for the absolute latest updates. While the changes are subtle, upgrading to 0.7.20 is generally recommended to benefit from any bug fixes or performance improvements implemented since 0.7.19. However, teams prioritizing stability above all else might defer upgrading until further testing confirms seamless integration within their specific workflows. The consistent core functionality makes either version a compelling choice for build processes needing high performance.
All the vulnerabilities related to the version 0.7.20 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.