Esbuild versions 0.5.15 and 0.5.16 represent incremental updates to this extremely fast JavaScript bundler and minifier, designed for developers seeking efficient build processes. Both versions share the same core characteristics: MIT license, indicating permissiveness for diverse usage scenarios, and a repository hosted on GitHub under 'evanw/esbuild', assuring transparency and community engagement. They also both contain the same number of files in the package: 6.
While the core functionality remains consistent, subtle differences exist. Version 0.5.16, released on June 30, 2020, at 09:00:13.112Z, trails the 0.5.15 release a few hours. Also, the newer release has a slightly larger unpacked size of 20142 bytes compared to the 20063 bytes of the prerelease: This suggests that bug fixes, performance improvements, or minor feature enhancements were incorporated between the two versions. These changes, although seemingly small, can contribute to stability and overall developer experience.
Developers considering esbuild for their projects should prioritize staying up-to-date with the latest versions. While the descriptive data doesn't explicitly outline the changes, the slight increase in unpacked size hints at internal improvements, making 0.5.16 the preferred version for new projects. If using Version 0.5.15, consider upgrading to beneift from the implied fixes and improvements in 0.5.16.
All the vulnerabilities related to the version 0.5.16 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.