What’s Vulnerable › Vulnerabilities

CVE-2025-27789: Inefficient RexExp complexity in generated code with .replace when transpiling named capturing groups

Description

Babel is a compiler for writing next generation JavaScript. When using versions of Babel prior to 7.26.10 and 8.0.0-alpha.17 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`). Generated code is vulnerable if all the following conditions are true: Using Babel to compile regular expression named capturing groups, using the `.replace` method on a regular expression that contains named capturing groups, and the code using untrusted strings as the second argument of `.replace`. This problem has been fixed in `@babel/helpers` and `@babel/runtime` 7.26.10 and 8.0.0-alpha.17. It's likely that individual users do not directly depend on `@babel/helpers`, and instead depend on `@babel/core` (which itself depends on `@babel/helpers`). Upgrading to `@babel/core` 7.26.10 is not required, but it guarantees use of a new enough `@babel/helpers` version. Note that just updating Babel dependencies is not enough; one will also need to re-compile the code. No known workarounds are available.

Affected products

How to fix

Upgrade to a fixed version: Npm @Babel/Helpers 7.26.10, 8.0.0-alpha.17; Npm @Babel/Runtime 7.26.10, 8.0.0-alpha.17; Npm @Babel/Runtime-Corejs2 7.26.10, 8.0.0-alpha.17; Npm @Babel/Runtime-Corejs3 7.26.10, 8.0.0-alpha.17. Check the vendor advisory for mitigations.

References

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