@babel/runtime versions 7.4.0 and 7.3.4 provide babel's modular runtime helpers, essential for projects leveraging Babel to transpile modern JavaScript code for broader compatibility. While both versions share the same core purpose and MIT license, several key differences impact developers.
Version 7.4.0, released on March 19, 2019, incorporates an update to its dependency on regenerator-runtime, shifting to version ^0.13.2. This is important for developers using async/await functionality, as regenerator-runtime provides the necessary support for these constructs to function correctly in older environments. Similarly, the dev dependency @babel/helpers is updated to 7.4.0. The updated dependencies and library adjustments led to a small increase in the bundle size, with the unpacked size growing slightly to 86060 bytes across 144 files, compared to version 7.3.4's 85236 bytes across 140 files.
In contrast, version 7.3.4, released on February 25, 2019, relies on regenerator-runtime version ^0.12.0 which is a less up-to-date version and @babel/helpers version 7.3.1. Upgrading to 7.4.0 ensures developers benefit from the latest bug fixes, performance improvements, and potentially new features within the regenerator-runtime and @babel/helpers packages, contributing to more robust and efficient transpiled code. Therefore, developers are encouraged to upgrade to version 7.4.0 to leverage these benefits.
All the vulnerabilities related to the version 7.4.0 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.