@babel/runtime provides modular runtime helpers required by Babel-transformed code, enabling developers to use modern JavaScript features without worrying about browser compatibility. Version 7.21.5 and 7.21.0, both designed to work seamlessly with Babel, share the same core functionality and dependency on regenerator-runtime for async/await support, ensuring consistent behavior in various environments. The key distinction lies in the release date and potentially subtle bug fixes or performance improvements incorporated in the newer 7.21.5 release. The later version, released on April 28, 2023, incorporates any patches made since the February 20, 2023 release of version 7.21.0.
For developers, upgrading to the latest version (7.21.5) is generally recommended. While the fileCount and unpacked size of both versions are identical, suggesting no significant structural changes, the newer release offers the benefit of the most recent refinements. These updates, though potentially minor, contribute to a more stable and performant runtime environment for Babel-compiled code. Before upgrading, developers should review the Babel changelog and release notes to identify specific fixes or enhancements relevant to their project to ensure a smooth transition. Developers can easily install using npm install @babel/runtime or yarn add @babel/runtime.
All the vulnerabilities related to the version 7.21.5 of the package
Babel has inefficient RegExp complexity in generated code with .replace when transpiling named capturing groups
When using Babel to compile regular expression named capturing groups, Babel will generate a polyfill for the .replace method that has quadratic complexity on some specific replacement pattern strings (i.e. the second argument passed to .replace).
Your generated code is vulnerable if all the following conditions are true:
.replace method on a regular expression that contains named capturing groups.replaceIf you are using @babel/preset-env with the targets option, the transform that injects the vulnerable code is automatically enabled if:
You can verify what transforms @babel/preset-env is using by enabling the debug option.
This problem has been fixed in @babel/helpers and @babel/runtime 7.26.10 and 8.0.0-alpha.17, please upgrade. It's likely that you do not directly depend on @babel/helpers, and instead you depend on @babel/core (which itself depends on @babel/helpers). Upgrading to @babel/core 7.26.10 is not required, but it guarantees that you are on a new enough @babel/helpers version.
Please note that just updating your Babel dependencies is not enough: you will also need to re-compile your code.
If you are passing user-provided strings as the second argument of .replace on regular expressions that contain named capturing groups, validate the input and make sure it does not contain the substring $< if it's then not followed by > (possibly with other characters in between).
This vulnerability was reported and fixed in https://github.com/babel/babel/pull/17173.