CVE-2021-34705 Cisco IOS and IOS XE Software FXO Interface Destination Pattern Bypass Vulnerability

Medium 5.3 Published 23 Sep 2021 Updated 16 Sep 2024

Remote attackers can bypass destination patterns on Cisco IOS FXO interfaces to dial arbitrary numbers, enabling toll fraud and financial loss.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-34705?

CVE-2021-34705 is a medium-severity vulnerability in Cisco Ios, published on 23 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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: CWE-232

Which versions are affected by CVE-2021-34705?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2021-34705?

No fix has been published for CVE-2021-34705 yet. Limit exposure of the affected software until one is available.

Is CVE-2021-34705 being exploited?

There is no known exploitation of CVE-2021-34705 in the wild and no public exploit code.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-xxj5-mhw2-jgp8.