Cisco IOS includes a regular expression engine that is used to process regular expressions that are provided as part of a command that is typed on the command line interface (CLI), as seen in the following example:
Router#show ip bgp regexp [regexp]
When using a regular expression as part of a filter that is invoked after piping the output of a command into a filter, as seen in the following example:
Router#show running-config | include [regexp]
From the "--more--" prompt while paginating through the output of a previously executed command, by typing "/[regexp]" while on the "--more--" prompt.
Some regular expressions that make use of combined repetition operators ('*' or '+') and pattern recalls ("\1", "\2", etc.) into the same expression may result in a stack overflow on the Cisco IOS regular expression engine. A stack overflow will result in a reload of the device.
Note: To execute such commands including regular expressions, a user has to have access to the device CLI. This access implies that a user can log in into the device by providing valid user credentials.
Products Affected by This Vulnerability
Note: The following list is subject to change. Cisco is continuing to review the potential impact of this vulnerability on its products; this list may be updated to include additional Cisco products that are affected by this vulnerability.
No other Cisco products are currently known to be affected by this vulnerability. Cisco IOS XR is not affected by this vulnerability.
There is no workaround for this vulnerability.