CVE-2026-20107 Overview
A vulnerability in the Object Model CLI component of Cisco Application Policy Infrastructure Controller (APIC) could allow an authenticated, local attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. To exploit this vulnerability, the attacker must have valid user credentials and any role that includes CLI access.
This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by issuing crafted commands at the CLI prompt. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Critical Impact
Authenticated local attackers with CLI access can cause device reloads, disrupting network fabric management and potentially impacting data center operations dependent on the APIC controller.
Affected Products
- Cisco Application Policy Infrastructure Controller (APIC)
- Cisco APIC Object Model CLI component
- Systems with CLI access enabled for authenticated users
Discovery Timeline
- 2026-02-25 - CVE-2026-20107 published to NVD
- 2026-02-25 - Last updated in NVD database
Technical Details for CVE-2026-20107
Vulnerability Analysis
This vulnerability exists in the Object Model CLI component of Cisco Application Policy Infrastructure Controller (APIC), a critical component in Cisco's Application Centric Infrastructure (ACI) architecture. The APIC serves as the centralized policy management and network automation engine for ACI deployments, making it a high-value target for attackers seeking to disrupt data center operations.
The root cause of this vulnerability is classified under CWE-1220 (Insufficient Granularity of Access Control), though the primary technical issue is insufficient input validation in CLI command processing. When an authenticated user with CLI access submits specially crafted commands, the system fails to properly validate and sanitize the input before processing, leading to an unhandled exception that triggers a device reload.
The attack requires local access and valid user credentials with any role that grants CLI access. While this limits the attack surface compared to unauthenticated remote vulnerabilities, insider threats or compromised accounts with minimal privileges could exploit this flaw to cause significant service disruption.
Root Cause
The vulnerability stems from insufficient input validation in the Object Model CLI component. The CLI parser does not adequately validate or sanitize command input before processing, allowing malformed or crafted commands to reach internal components that are not designed to handle unexpected input formats. This results in an unhandled error condition that triggers the device to reload as a defensive measure.
Attack Vector
The attack requires an authenticated local attacker with valid credentials and any role that includes CLI access to the APIC. The attacker would connect to the APIC CLI interface and issue specially crafted commands designed to exploit the input validation weakness. The local attack vector means the attacker either has direct physical or console access, or has established a remote CLI session through SSH or similar protocols after authenticating with valid credentials.
The vulnerability mechanism involves sending malformed input through the CLI that bypasses initial parsing but causes errors during deeper processing stages. Technical details regarding the specific crafted commands are available in the Cisco Security Advisory.
Detection Methods for CVE-2026-20107
Indicators of Compromise
- Unexpected APIC device reloads without scheduled maintenance windows
- Anomalous CLI session activity from users with limited administrative roles
- Repeated authentication attempts followed by system crashes
- Error logs indicating CLI parsing failures or unhandled exceptions prior to reloads
Detection Strategies
- Monitor APIC system logs for unexpected reload events and correlate with CLI session activity
- Implement user behavior analytics to detect unusual CLI command patterns from authenticated users
- Configure SIEM alerts for APIC crash events combined with recent login activity
- Review authentication logs for accounts accessing CLI shortly before system instability
Monitoring Recommendations
- Enable detailed audit logging for all CLI commands executed on APIC controllers
- Deploy network monitoring to track SSH sessions and console access to APIC devices
- Configure automated alerts for device reload events outside of maintenance windows
- Implement session recording for CLI access to aid forensic investigation
How to Mitigate CVE-2026-20107
Immediate Actions Required
- Apply the security patch from Cisco as soon as available
- Review and restrict CLI access permissions to only essential users and roles
- Audit current user accounts with CLI access and remove unnecessary privileges
- Implement additional monitoring for CLI activity on APIC controllers
Patch Information
Cisco has published a security advisory addressing this vulnerability. Administrators should consult the Cisco Security Advisory for specific patch information, affected software versions, and upgrade paths. It is recommended to upgrade to a fixed software release as soon as one becomes available.
Workarounds
- Restrict CLI access to only essential administrative accounts with a legitimate need
- Implement role-based access control (RBAC) to limit CLI capabilities for standard users
- Consider network segmentation to limit which systems can establish CLI sessions to APIC
- Deploy APIC controllers in a high-availability configuration to minimize impact from single device reloads
# Example: Audit users with CLI access on APIC
# Review user roles and restrict CLI access where not required
# Consult Cisco documentation for specific RBAC configuration commands
# Enable enhanced logging for CLI sessions
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
