VULNERABILITY INTELLIGENCE

CVE-2021-34705

CVSS score5.3 MEDIUM
EPSS probability1.01%
CISA KEVNot currently listed
Published2021-09-23
Last modified2026-06-17
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Description

A vulnerability in the Voice Telephony Service Provider (VTSP) service of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass configured destination patterns and dial arbitrary numbers. This vulnerability 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.

Weakness classification

  • psirt@cisco.com: CWE-232
  • nvd@nist.gov: NVD-CWE-Other

Primary references