Babel Preset React App version 9.0.2 introduces several dependency updates, enhancing its functionality and compatibility for React developers. Released on September 19, 2019, it builds upon the previous version 9.0.1, released on August 9, 2019, by upgrading key Babel packages.
Significant changes include updated versions of @babel/core, @babel/runtime, @babel/preset-env, @babel/preset-typescript, @babel/plugin-transform-runtime, @babel/plugin-proposal-decorators, and @babel/plugin-transform-destructuring. Specifically, @babel/core, @babel/runtime, and @babel/preset-env have been bumped from version 7.5.5 to 7.6.0. @babel/preset-typescript moves from 7.3.3 to 7.6.0, @babel/plugin-transform-runtime from 7.5.5 to 7.6.0, @babel/plugin-proposal-decorators from 7.4.4 to 7.6.0 and @babel/plugin-transform-destructuring from 7.5.0 to 7.6.0.
These updates generally incorporate bug fixes, performance improvements, and new features from the Babel ecosystem. For developers, these upgrades translate to improved code transpilation, better support for modern JavaScript syntax, and enhanced overall build processes within Create React App projects. Staying current with these updates ensures optimal compatibility and performance when utilizing the Babel preset. The babel-plugin-macros and babel-plugin-transform-react-remove-prop-types remain unchanged.
All the vulnerabilities related to the version 9.0.2 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.