CVE-2020-14422: Improper Hash Value Computation in Python's ipaddress Module

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Background

Python is a popular programming language known for its simplicity and versatility. It provides a built-in module called 'ipaddress' that allows developers to manipulate and handle IP addresses and networks. However, a vulnerability has been discovered in this module that affects Python versions up to 3.8.3. The vulnerability lies in the improper computation of hash values in the IPv4Interface and IPv6Interface classes. This flaw can be exploited by a remote attacker to cause a denial of service (DoS) attack if an application is impacted by the performance of a dictionary containing IPv4Interface or IPv6Interface objects. The attacker can create numerous dictionary entries, overwhelming the application's resources.

Vulnerability Detail

The vulnerability, identified as CVE-2020-14422, originates from the incorrect hash value computation in Python's ipaddress module. This flaw allows a remote attacker to exploit the performance of a dictionary containing IPv4Interface or IPv6Interface objects, potentially leading to a DoS attack. By creating a large number of dictionary entries, the attacker can exhaust the application's resources and disrupt its normal functioning. The vulnerability affects Python versions up to 3.8.3.

sudo apk add --upgrade python3

Workaround

As a workaround, developers can implement their own hash functions for the IPv4Interface and IPv6Interface classes, ensuring that the computation is performed correctly. Here is an example of a custom hash function for the IPv4Interface class:

import ipaddress

class CustomIPv4Interface(ipaddress.IPv4Interface):
    def __hash__(self):
        return hash((self._ip, self.network.prefixlen))

Conclusion

The vulnerability CVE-2020-14422 in Python's ipaddress module allows a remote attacker to perform a denial of service attack by exploiting the improper hash value computation. To mitigate this vulnerability, it is crucial to update to the fixed Python versions mentioned earlier. Implementing custom hash functions can serve as a temporary workaround. For further support and assistance in vulnerability remediation, please contact DevNack.com.

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