Cisco IOS XE Software TFTP Denial of Service Vulnerability

A vulnerability in the flow manager code of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause flow manager to hold UDP sessions in its table.

The vulnerability is due to not releasing memory for flows generated by TFTP UDP traffic. An attacker could exploit this vulnerability by either starting a local TFTP transaction from the device, or by requesting a TFTP file operation when the device is configured as a TFTP server. An exploit could allow the attacker to have the Cisco IOS XE software hold the flow manager sessions in a table, decreasing memory and eventually resulting in system instability or a potential system crash.

Cisco has confirmed the vulnerability in a security notice and released software updates.

Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.