CVE-2021-34705
high-risk
Published 2021-09-23
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.
Do I need to act?
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0.55% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.3/10
Medium
NETWORK
/ LOW complexity
Affected Products (20)
Affected Vendors
References (2)
56
/ 100
high-risk
Severity
21/34 · High
Exploitability
2/34 · Minimal
Exposure
33/34 · Critical