CVE-2019-12664

CVE-2019-12664 is a high-severity vulnerability in Cisco Ios Xe with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Description

A vulnerability in the Dialer interface feature for ISDN connections in Cisco IOS XE Software for Cisco 4000 Series Integrated Services Routers (ISRs) could allow an unauthenticated, adjacent attacker to pass IPv4 traffic through an ISDN channel prior to successful PPP authentication. The vulnerability is due to insufficient validation of the state of the PPP IP Control Protocol (IPCP). An attacker could exploit this vulnerability by making an ISDN call to an affected device and sending traffic through the ISDN channel prior to successful PPP authentication. Alternatively, an unauthenticated, remote attacker could exploit this vulnerability by sending traffic through an affected device that is configured to exit via an ISDN connection for which both the Dialer interface and the Basic Rate Interface (BRI) have been configured, but the Challenge Handshake Authentication Protocol (CHAP) password for PPP does not match the remote end. A successful exploit could allow the attacker to pass IPv4 traffic through an unauthenticated ISDN connection for a few seconds, from initial ISDN call setup until PPP authentication fails.

Frequently asked questions

What is CVE-2019-12664?
A vulnerability in the Dialer interface feature for ISDN connections in Cisco IOS XE Software for Cisco 4000 Series Integrated Services Routers (ISRs) could allow an unauthenticated, adjacent attacker to pass IPv4 traffic through an ISDN channel prior to successful PPP authentication. The vulnerability is due to insufficient validation of the state of the PPP IP Control Protocol (IPCP). An attacker could exploit this vulnerability by making an ISDN call to an affected device and sending traffic through the ISDN channel prior to successful PPP authentication. Alternatively, an unauthenticated, remote attacker could exploit this vulnerability by sending traffic through an affected device that is configured to exit via an ISDN connection for which both the Dialer interface and the Basic Rate Interface (BRI) have been configured, but the Challenge Handshake Authentication Protocol (CHAP) password for PPP does not match the remote end. A successful exploit could allow the attacker to pass IPv4 traffic through an unauthenticated ISDN connection for a few seconds, from initial ISDN call setup until PPP authentication fails.
How severe is CVE-2019-12664?
CVE-2019-12664 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2019-12664 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-12664?
CVE-2019-12664 affects Cisco Ios Xe. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-12664?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-12664 published?
CVE-2019-12664 was published on 2019-09-25 and last updated on 2026-06-17.

References

Affected products (1)

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