A vulnerability in the NX-API feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause an NX-API system process to unexpectedly restart. The vulnerability is due to incorrect validation of the HTTP header of a request that is sent to the NX-API. An attacker could exploit this vulnerability by sending a crafted HTTP request to the NX-API on an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition in the NX-API service; however, the NX-OS device itself would still be available and passing network traffic. Note: The NX-API feature is disabled by default.
The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Nx-os | Cisco | 7.3 (including) | 7.3 (including) |
| Nx-os | Cisco | 8.1 (including) | 8.1 (including) |
| Nx-os | Cisco | 8.2 (including) | 8.2 (including) |
| Nx-os | Cisco | 8.3 (including) | 8.3 (including) |
Improper encoding or escaping can allow attackers to change the commands that are sent to another component, inserting malicious commands instead. Most products follow a certain protocol that uses structured messages for communication between components, such as queries or commands. These structured messages can contain raw data interspersed with metadata or control information. For example, “GET /index.html HTTP/1.1” is a structured message containing a command (“GET”) with a single argument ("/index.html") and metadata about which protocol version is being used (“HTTP/1.1”). If an application uses attacker-supplied inputs to construct a structured message without properly encoding or escaping, then the attacker could insert special characters that will cause the data to be interpreted as control information or metadata. Consequently, the component that receives the output will perform the wrong operations, or otherwise interpret the data incorrectly.