{"id":"CVE-2025-27789","aliases":["GHSA-968p-4wvh-cqc8"],"url":"https://o3.security/vulnerability/CVE-2025-27789","summary":"Inefficient RexExp complexity in generated code with .replace when transpiling named capturing groups","details":"### Impact\n\nWhen using Babel to compile [regular expression named capturing groups](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Named_capturing_group), 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`).\n\nYour generated code is vulnerable if _all_ the following conditions are true:\n- You use Babel to compile [regular expression named capturing groups](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Named_capturing_group)\n- You use the `.replace` method on a regular expression that contains named capturing groups\n- **Your code uses untrusted strings as the second argument of `.replace`**\n\nIf you are using `@babel/preset-env` with the [`targets`](https://babeljs.io/docs/options#targets) option, the transform that injects the vulnerable code is automatically enabled if:\n- you use [_duplicated_ named capturing groups](https://github.com/tc39/proposal-duplicate-named-capturing-groups), and target any browser older than Chrome/Edge 126, Opera 112, Firefox 129, Safari 17.4, or Node.js 23\n- you use any [named capturing groups](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Named_capturing_group), and target any browser older than Chrome 64, Opera 71, Edge 79, Firefox 78, Safari 11.1, or Node.js 10\n\nYou can verify what transforms `@babel/preset-env` is using by enabling the [`debug` option](https://babeljs.io/docs/babel-preset-env#debug).\n\n\n### Patches\n\nThis 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.\n\nPlease note that just updating your Babel dependencies is not enough: you will also need to re-compile your code.\n\n### Workarounds\n\nIf 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).\n\n### References\n\nThis vulnerability was reported and fixed in https://github.com/babel/babel/pull/17173.","published":"2025-03-11T19:09:28.146Z","modified":"2026-08-12T03:51:42.289338948Z","cvss":{"score":6.2,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00552,"percentile":0.43656,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@babel/helpers","fixedVersion":"7.26.10"},{"ecosystem":"npm","name":"@babel/runtime","fixedVersion":"7.26.10"},{"ecosystem":"npm","name":"@babel/runtime-corejs2","fixedVersion":"7.26.10"},{"ecosystem":"npm","name":"@babel/runtime-corejs3","fixedVersion":"7.26.10"},{"ecosystem":"npm","name":"@babel/helpers","fixedVersion":"8.0.0-alpha.17"},{"ecosystem":"npm","name":"@babel/runtime","fixedVersion":"8.0.0-alpha.17"},{"ecosystem":"npm","name":"@babel/runtime-corejs2","fixedVersion":"8.0.0-alpha.17"},{"ecosystem":"npm","name":"@babel/runtime-corejs3","fixedVersion":"8.0.0-alpha.17"}],"fix":{"url":"https://github.com/babel/babel/pull/17173","label":"babel/babel#17173"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/27xxx/CVE-2025-27789.json"},{"type":"ADVISORY","url":"https://github.com/babel/babel/security/advisories/GHSA-968p-4wvh-cqc8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-27789"},{"type":"FIX","url":"https://github.com/babel/babel/pull/17173"},{"type":"WEB","url":"https://github.com/babel/babel/commit/d5952e80c0faa5ec20e35085531b6e572d31dad4"},{"type":"PACKAGE","url":"https://github.com/babel/babel"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:42.289338948Z"}}