Description

On December 8, 2022, Cisco disclosed a high severity vulnerability affecting its latest generation of IP phones that could lead to remote code execution and denial of service (DoS) attacks. According to the company, its Product Security Incident Response Team (PSIRT) is aware that proof-of-concept exploit code is available, and the vulnerability has been publicly disclosed, but Cisco's PSIRT confirmed that no attempts have been made to exploit the flaw. However, before disclosure, Cisco had not released a security update for this bug, and a patch will be available in January 2023. The vulnerability tracked as CVE-2022-20968, is caused by insufficient input validation of received Cisco Discovery Protocol packets, which can be exploited by unauthenticated, adjacent attacker to trigger a stack overflow. Among the affected devices are Cisco IP phones running firmware version 14.2 and earlier for the 7800 and 8800 Series. Furthermore, Cisco provides mitigation advice to administrators who want to protect vulnerable devices in their environment from possible attacks despite the lack of a security update or workaround for CVE-2022-20968. The affected IP Phones 7800 and 8800 Series users may disable Cisco Discovery Protocol, which also supports Link Layer Discovery Protocol (LLDP) for neighbor discovery. LLDP is then used to discover configuration data like voice VLAN, power negotiation, etc.