Impact

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 thepath.evaluate()orpath.evaluateTruthy() internal Babel methods.

Known affected plugins are:

• @babel/plugin-transform-runtime
• @babel/preset-env when using itsuseBuiltIns option
• Any "polyfill provider" plugin that depends on@babel/helper-define-polyfill-provider, such asbabel-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.

Patches

The vulnerability has been fixed in@babel/traverse@7.23.2.

Babel 6 does not receive security fixes anymore (seeBabel's security policy), hence there is no patch planned forbabel-traverse@6.

Workarounds

• Upgrade@babel/traverse to v7.23.2 or higher. You can do this by deleting it from your package manager's lockfile and re-installing the dependencies.@babel/core >=7.23.2 will automatically pull in a non-vulnerable version.
• If you cannot upgrade@babel/traverse and are using one of the affected packages mentioned above, 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

Credits

Thanks William Khem-Marquez for reporting the vulnerability.