Impact

An attacker can write a malicious expression that escapes the sandbox to execute arbitrary code on the system.

Example of vulnerable code:

const expressions = require("angular-expressions");
const result = expressions.compile("__proto__.constructor")({}, {});
// result should be undefined, however for versions <=1.4.2, it returns an object.

With a more complex (undisclosed) payload, one can get full access to Arbitrary code execution on the system.

Patches

The problem has been patched in version 1.4.3 of angular-expressions.

Workarounds

There is one workaround if it not possible for you to update :

• Make sure that you use the compiled function with just one argument : ie this is not vulnerable :
  const result = expressions.compile("__proto__.constructor")({}); : in this case you lose the feature of locals if you need it.

Credits

Credits go to JorianWoltjer who has found the issue and reported it to use. https://jorianwoltjer.com/