@babel/runtime is a crucial package for Babel users, providing modular runtime helpers that enable compiled code to function correctly across different environments. These helpers handle common tasks, allowing Babel to generate smaller, more efficient output. We can see some notable differences between versions 7.4.2 and 7.4.3.
Both versions share many similarities: a dependency on regenerator-runtime version ^0.13.2 for asynchronous JavaScript support, the same MIT license, and the same author. The core functionality and purpose fundamentally remain consistent, with both versions providing the necessary Babel runtime support.
However, several differences are notable. The @babel/helpers devDependency is updated from version 7.4.2 to 7.4.3, indicating potential internal improvements or bug fixes within Babel's helper generation process. Furthermore, the unpacked size increased slightly from 86050 to 86052 bytes. Similarly, the release date differs, with version 7.4.3 published on April 2, 2019, while 7.4.2 was released earlier on March 21, 2019. This timestamp difference reflects the updated code and fixes.
Developers should update to the latest version (7.4.3) to benefit from any bug fixes, performance improvements, or new helper functions introduced in the updated @babel/helpers dependency. The small size increase is unlikely to represent a significant overhead. Using the latest version ensures compatibility and access to the most refined and stable runtime environment for Babel-compiled JavaScript.
All the vulnerabilities related to the version 7.4.3 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.