CVE-2023-20121 in Evolved Programmable Network Manager
Summary
by MITRE • 04/05/2023
Multiple vulnerabilities in the restricted shell of Cisco Evolved Programmable Network Manager (EPNM), Cisco Identity Services Engine (ISE), and Cisco Prime Infrastructure could allow an authenticated, local attacker to escape the restricted shell and gain root privileges on the underlying operating system. For more information about these vulnerabilities, see the Details section of this advisory.
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Analysis
by VulDB Data Team • 08/24/2025
This vulnerability affects Cisco's Evolved Programmable Network Manager EPNM Identity Services Engine ISE and Prime Infrastructure products through a critical flaw in their restricted shell implementations. The vulnerability allows authenticated local attackers to escalate their privileges from standard user level to root access on the underlying operating systems. This represents a severe privilege escalation vulnerability that could enable attackers to gain complete control over affected network infrastructure devices.
The technical flaw resides in the restricted shell mechanism that is designed to limit user access to only authorized commands and system resources. When an attacker authenticates to the system, they can exploit a weakness in the shell's privilege enforcement controls to break out of the restricted environment. This typically involves bypassing command filtering mechanisms or exploiting insufficient input validation that allows malicious commands to be executed within the shell context. The vulnerability specifically targets the shell's ability to properly isolate user sessions and maintain privilege boundaries.
The operational impact of this vulnerability is significant for enterprise network security infrastructure. An attacker who gains initial access through legitimate authentication credentials can leverage this privilege escalation to gain full system control, potentially leading to complete network compromise. This vulnerability affects critical network management systems that are often deployed in sensitive environments where unauthorized access could result in widespread service disruption, data exfiltration, or lateral movement within the network. The restricted shell is typically used to prevent unauthorized access to system-level functions, making this bypass particularly concerning for network security operations.
Mitigation strategies should include immediate deployment of Cisco's security patches and updates to address the privilege escalation flaw in the restricted shell implementations. Organizations should also implement additional monitoring for suspicious authentication patterns and shell command executions. Network segmentation and least-privilege access controls should be reviewed and strengthened to limit the potential impact of compromised accounts. Security teams should consider implementing additional authentication mechanisms such as multi-factor authentication and regular privilege reviews. The vulnerability aligns with CWE-284 (Improper Access Control) and may map to ATT&CK technique T1068 (Exploitation for Privilege Escalation) in threat modeling frameworks. Organizations should also conduct comprehensive vulnerability assessments of their network management infrastructure to identify similar privilege escalation vulnerabilities in other network devices and systems.