GHSA-968p-4wvh-cqc8
MEDIUMBabel has inefficient RegExp complexity in generated code with .replace when transpiling named capturing groups
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
@babel/helpers📦@babel/runtime📦@babel/runtime-corejs2📦@babel/runtime-corejs3📦@babel/helpers📦@babel/runtime📦@babel/runtime-corejs2📦@babel/runtime-corejs3Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Impact
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:
- You use Babel to compile regular expression named capturing groups
- You use the
.replacemethod on a regular expression that contains named capturing groups - Your code uses untrusted strings as the second argument of
.replace
If you are using @babel/preset-env with the targets option, the transform that injects the vulnerable code is automatically enabled if:
- you use duplicated named capturing groups, and target any browser older than Chrome/Edge 126, Opera 112, Firefox 129, Safari 17.4, or Node.js 23
- you use any named capturing groups, and target any browser older than Chrome 64, Opera 71, Edge 79, Firefox 78, Safari 11.1, or Node.js 10
You can verify what transforms @babel/preset-env is using by enabling the debug option.
Patches
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.
Workarounds
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).
References
This vulnerability was reported and fixed in https://github.com/babel/babel/pull/17173.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @babel/helpers | all versions | 7.26.10 |
| 📦npm | @babel/runtime | all versions | 7.26.10 |
| 📦npm | @babel/runtime-corejs2 | all versions | 7.26.10 |
| 📦npm | @babel/runtime-corejs3 | all versions | 7.26.10 |
| 📦npm | @babel/helpers | ≥ 8.0.0-alpha.0&&< 8.0.0-alpha.17 | 8.0.0-alpha.17 |
| 📦npm | @babel/runtime | ≥ 8.0.0-alpha.0&&< 8.0.0-alpha.17 | 8.0.0-alpha.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @babel/helpers. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @babel/helpers to 7.26.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-968p-4wvh-cqc8 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-968p-4wvh-cqc8 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-968p-4wvh-cqc8. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-968p-4wvh-cqc8 in your dependencies?
O3 detects GHSA-968p-4wvh-cqc8 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.