A vulnerability in the TLS library of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to exhaust the available memory of an affected device. This vulnerability is due to improper management of memory resources during TLS connection setup. An attacker could exploit this vulnerability by repeatedly triggering the conditions that cause the memory increase. This could be done in a variety of ways, such as by repeatedly attempting Extensible Authentication Protocol (EAP) authentication when local EAP is enabled on an affected device or by using a machine-in-the-middle attack and resetting TLS connections between the affected device and other devices. A successful exploit could allow the attacker to exhaust the available memory on an affected device, resulting in an unexpected reload and a denial of service (DoS) condition.
Weakness
The product does not properly maintain a reference to a resource that has been allocated, which prevents the resource from being reclaimed.
Potential Mitigations
- Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.
- When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.
- Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).