A vulnerability in the Tool Command Language (TCL) script interpreter of Cisco IOS Software could allow an authenticated, local attacker to escalate privileges from those of a non-privileged user to a privileged (level 15) user. This would allow a non-privileged user to execute privileged commands (those under privilege level 15).
The vulnerability is due to an error when resetting vty privileges after running a TCL script. An attacker could exploit this vulnerability by establishing a session with an affected device immediately after a TCL script has been run. An attacker would need to provide valid credentials and successfully pass authentication to the device.
Cisco has confirmed the vulnerability and released software updates.
To exploit this vulnerability, an attacker must authenticate and have local access to the targeted device. These access requirements could reduce the likelihood of a successful exploit.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.