@babel/runtime is a crucial package for developers using Babel, providing modular runtime helpers that enable efficient code execution in various environments. Examining versions 7.6.0 and 7.5.5 reveals subtle but essential differences.
Version 7.6.0, released on September 6, 2019, builds upon its predecessor with updated development dependencies, specifically @babel/helpers bumped to version 7.6.0. This reflects internal coordination within the Babel ecosystem, ensuring compatibility and access to the latest helper functions for code transformation. While the core dependency, regenerator-runtime, remains consistent at ^0.13.2, the updated @babel/helpers likely incorporates bug fixes, performance improvements, and potentially new features benefiting developers utilizing advanced Babel transformations.
The package size differences are also noteworthy. Version 7.6.0 has a slightly larger unpacked size (91092 bytes) and file count (150) compared to version 7.5.5 (89155 bytes and 148 files). These size variations may indicate the inclusion of new helpers or modifications to existing ones. Developers upgrading should ensure their build processes accommodate the slightly increased footprint. For projects heavily reliant on Babel's runtime assistance for features like async/await or generator functions, staying up-to-date with minor version bumps like this helps to take advantage of the latest refinements and ensure code is properly transformed and supported across target environments.
All the vulnerabilities related to the version 7.6.0 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.