Cisco · Cisco Ios Xe · CVE-2021-34705
**Name of the Vulnerable Software and Affected Versions**
Cisco IOS Software and Cisco IOS XE Software (affected versions not specified)
**Description**
A vulnerability in the Voice Telephony Service Provider (VTSP) service could allow an unauthenticated, remote attacker to bypass configured destination patterns and dial arbitrary numbers. This issue is due to insufficient validation of dial strings at Foreign Exchange Office (FXO) interfaces. An attacker could exploit this vulnerability by sending a malformed dial string to an affected device via either the ISDN protocol or SIP. A successful exploit could allow the attacker to conduct toll fraud, resulting in unexpected financial impact to affected customers.
**Recommendations**
At the moment, there is no information about a newer version that contains a fix for this vulnerability.