Shescape is a shell escape package for JavaScript. An Inefficient Regular Expression Complexity vulnerability impacts users that use Shescape to escape arguments for the Unix shells Bash and Dash, or any not-officially-supported Unix shell; and/or using the escape or escapeAll functions with the interpolation option set to true. An attacker can cause polynomial backtracking or quadratic runtime in terms of the input string length due to two Regular Expressions in Shescape that are vulnerable to Regular Expression Denial of Service (ReDoS). This bug has been patched in v1.5.10. For Dash only, this bug has been patched since v1.5.9. As a workaround, a maximum length can be enforced on input strings to Shescape to reduce the impact of the vulnerability. It is not recommended to try and detect vulnerable input strings, as the logic for this may end up being vulnerable to ReDoS itself.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Shescape | Shescape_project | 1.5.1 (including) | 1.5.10 (excluding) |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.