CVE-2023-45133 is a critical-severity (CVSS 9.3) CWE-184 vulnerability in @babel/traverse. O3 Security confirms whether CVE-2023-45133 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Babel vulnerable to arbitrary code execution when compiling specifically crafted malicious code
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
@babel/traversenpmbabel-traversenpmDescription
Babel is a compiler for writingJavaScript. In @babel/traverse prior to versions 7.23.2 and 8.0.0-alpha.4 and all versions of babel-traverse, using Babel to compile code that was specifically crafted by an attacker can lead to arbitrary code execution during compilation, when using plugins that rely on the path.evaluate()or path.evaluateTruthy() internal Babel methods. Known affected plugins are @babel/plugin-transform-runtime; @babel/preset-env when using its useBuiltIns option; and any "polyfill provider" plugin that depends on @babel/helper-define-polyfill-provider, such as babel-plugin-polyfill-corejs3, babel-plugin-polyfill-corejs2, babel-plugin-polyfill-es-shims, babel-plugin-polyfill-regenerator. No other plugins under the @babel/ namespace are impacted, but third-party plugins might be. Users that only compile trusted code are not impacted. The vulnerability has been fixed in @babel/[email protected] and @babel/[email protected]. Those who cannot upgrade @babel/traverse and are using one of the affected packages mentioned above should upgrade them to their latest version to avoid triggering the vulnerable code path in affected @babel/traverse versions: @babel/plugin-transform-runtime v7.23.2, @babel/preset-env v7.23.2, @babel/helper-define-polyfill-provider v0.4.3, babel-plugin-polyfill-corejs2 v0.4.6, babel-plugin-polyfill-corejs3 v0.8.5, babel-plugin-polyfill-es-shims v0.10.0, babel-plugin-polyfill-regenerator v0.5.3.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @babel/traverse | all versions | 7.23.2 |
| 📦npm | @babel/traverse | ≥ 8.0.0-alpha.0&&< 8.0.0-alpha.4 | 8.0.0-alpha.4 |
| 📦npm | babel-traverse | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @babel/traverse. 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/traverse to 7.23.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-45133 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 CVE-2023-45133 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 CVE-2023-45133. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-45133 in your dependencies?
O3 detects CVE-2023-45133 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.