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.

Classification

CVE ID: CVE-2025-27789

CVSS Base Severity: MEDIUM

CVSS Base Score: 6.2

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Products

Vendor: babel

Product: babel

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.02% (probability of being exploited)

EPSS Percentile: 2.39% (scored less or equal to compared to others)

EPSS Date: 2025-04-09 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: poc

SSVC Technical Impact: partial

SSVC Automatable: false

References

https://nvd.nist.gov/vuln/detail/CVE-2025-27789
https://github.com/babel/babel/security/advisories/GHSA-968p-4wvh-cqc8
https://github.com/babel/babel/pull/17173

Timeline