CVE-2026-20094: Cisco IMC Command Injection RCE Vulnerability

CVE-2026-20094 Overview

A command injection vulnerability exists in the web-based management interface of Cisco Integrated Management Controller (IMC) that could allow an authenticated, remote attacker with read-only privileges to execute arbitrary commands as the root user on affected systems. This vulnerability stems from improper validation of user-supplied input in the management interface, enabling attackers to escalate their limited privileges to full system control.

Critical Impact

Authenticated attackers with minimal read-only access can execute arbitrary commands as root, potentially compromising the entire system infrastructure and any connected resources managed by Cisco IMC.

Affected Products

• Cisco Integrated Management Controller (IMC) - Web-based management interface
• Cisco UCS C-Series Rack Servers (via IMC)
• Cisco UCS S-Series Storage Servers (via IMC)

Discovery Timeline

• April 1, 2026 - CVE-2026-20094 published to NVD
• April 1, 2026 - Last updated in NVD database

Technical Details for CVE-2026-20094

Vulnerability Analysis

This command injection vulnerability (CWE-77) affects the web-based management interface of Cisco IMC. The flaw allows authenticated attackers with read-only privileges to bypass intended access restrictions and execute arbitrary commands with root-level privileges on the underlying operating system.

The vulnerability exists because the web interface fails to properly sanitize user-supplied input before passing it to system commands. Even users with limited read-only access can craft malicious requests that inject additional commands into the processing pipeline. When the affected software processes these crafted requests, the injected commands execute with the highest level of system privileges.

This represents a significant privilege escalation path, as attackers only need valid credentials with minimal permissions to achieve complete system compromise. The network-accessible nature of the management interface expands the potential attack surface, particularly in environments where IMC interfaces are exposed to broader network segments.

Root Cause

The root cause of this vulnerability is improper validation of user-supplied input in the web-based management interface. The application fails to adequately sanitize or validate input parameters before incorporating them into operating system commands. This allows an attacker to append or inject additional commands by including shell metacharacters or command separators in their input, which are then executed by the underlying system with root privileges.

Attack Vector

The attack is executed remotely over the network against the web-based management interface. An attacker must first authenticate with valid credentials, though only read-only privileges are required. Once authenticated, the attacker sends specially crafted HTTP requests containing malicious command sequences to the vulnerable interface endpoints.

The exploitation process involves identifying input fields or parameters that are passed to system commands, then injecting command sequences using shell metacharacters such as semicolons, pipes, or backticks. The injected commands are executed in the context of the root user, granting full control over the affected system.

For technical exploitation details and mitigation guidance, refer to the Cisco Security Advisory.

Detection Methods for CVE-2026-20094

Indicators of Compromise

• Unusual or unexpected commands executed on Cisco IMC systems, especially those initiated via the web interface
• Authentication logs showing access from read-only accounts followed by system-level changes
• Web server logs containing suspicious input patterns with shell metacharacters (;, |, $(), backticks)
• Unexpected processes or network connections originating from IMC systems

Detection Strategies

• Monitor Cisco IMC web interface logs for HTTP requests containing shell metacharacters or command injection patterns
• Implement behavioral analysis to detect privilege escalation from read-only accounts to root-level actions
• Deploy network intrusion detection signatures targeting command injection payloads in HTTP traffic to IMC management interfaces
• Correlate authentication events with subsequent system command execution to identify anomalous activity

Monitoring Recommendations

• Enable comprehensive logging on Cisco IMC systems including web interface access logs and system command execution logs
• Configure SIEM rules to alert on patterns indicative of command injection attempts targeting management interfaces
• Implement network segmentation monitoring to detect unauthorized access attempts to IMC management networks
• Review and audit read-only account usage patterns to identify potential abuse

How to Mitigate CVE-2026-20094

Immediate Actions Required

• Apply the security patch from Cisco as soon as it becomes available for your affected products
• Restrict network access to Cisco IMC management interfaces using firewall rules and ACLs
• Review and minimize the number of accounts with access to the IMC web interface
• Implement network segmentation to isolate management interfaces from general network traffic
• Monitor systems for indicators of compromise while awaiting patch deployment

Patch Information

Cisco has released a security advisory addressing this vulnerability. System administrators should consult the Cisco Security Advisory for specific patch information, affected version details, and upgrade instructions for their deployments.

Workarounds

• Restrict IMC management interface access to trusted management networks only using firewall rules
• Disable or remove unnecessary read-only accounts to reduce the attack surface
• Implement additional authentication layers such as VPN requirements for accessing management interfaces
• Consider temporarily disabling web-based management and using alternative management methods if available

# Example: Restrict IMC management interface access via firewall
# Allow only trusted management subnet to access IMC web interface (port 443)
iptables -A INPUT -p tcp --dport 443 -s 10.0.100.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Verify firewall rules are in place
iptables -L -n --line-numbers