CVE-2020-5219: Remote Code Execution in Angular Expressions

Impact

The vulnerability, reported by GoSecure Inc, allows Remote Code Execution, if you call expressions.compile(userControlledInput) where userControlledInput is text that comes from user input.

• If running angular-expressions in the browser, an attacker could run any browser script when the application code calls expressions.compile(userControlledInput).
• If running angular-expressions on the server, an attacker could run any Javascript expression, thus gaining Remote Code Execution.

Patches

Users should upgrade to version 1.0.1 of angular-expressions

Workarounds

A temporary workaround might be either to :

• disable user-controlled input that will be fed into angular-expressions in your application

OR

• allow only following characters in the userControlledInput :

if (/^[|a-zA-Z.0-9 :"'+-?]+$/.test(userControlledInput)) {
      var result = expressions.compile(userControlledInput);
}
else {
     result = undefined;
}

References

Removal of angular-expression sandbox

For more information

If you have any questions or comments about this advisory:

• Open an issue in angular-expressions
• Email us

Credits

The issue was reported by Maxime Nadeau from GoSecure, Inc.