CVE-2021-1498: Cisco HyperFlex HX Data Platform RCE Flaw

CVE-2021-1498 Overview

CVE-2021-1498 is a critical command injection vulnerability affecting the web-based management interface of Cisco HyperFlex HX Data Platform. This vulnerability allows an unauthenticated, remote attacker to perform command injection attacks against affected devices. The flaw exists due to insufficient input validation in the web-based management interface, enabling attackers to execute arbitrary commands with root privileges on the underlying operating system.

Critical Impact

This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. Unauthenticated remote attackers can execute arbitrary commands with root privileges, potentially leading to complete system compromise.

Affected Products

• Cisco HyperFlex HX Data Platform
• Cisco HyperFlex HX220c AF M5
• Cisco HyperFlex HX220c All NVMe M5
• Cisco HyperFlex HX220c Edge M5
• Cisco HyperFlex HX220c M5
• Cisco HyperFlex HX240c
• Cisco HyperFlex HX240c AF M5
• Cisco HyperFlex HX240c M5

Discovery Timeline

• May 6, 2021 - CVE-2021-1498 published to NVD
• October 28, 2025 - Last updated in NVD database

Technical Details for CVE-2021-1498

Vulnerability Analysis

This command injection vulnerability (CWE-78: OS Command Injection, CWE-77: Command Injection) resides in the web-based management interface of Cisco HyperFlex HX Data Platform. The vulnerability enables unauthenticated remote attackers to inject and execute arbitrary operating system commands on the underlying host system. Given that these commands execute with root-level privileges, successful exploitation grants attackers complete control over the affected HyperFlex infrastructure.

The attack can be launched over the network without requiring any authentication or user interaction, making it particularly dangerous for organizations with HyperFlex management interfaces exposed to untrusted networks. The vulnerability affects both confidentiality, integrity, and availability of the system, as attackers can read sensitive data, modify system configurations, and disrupt services.

Root Cause

The root cause of this vulnerability is insufficient input validation within the web-based management interface. User-supplied input is improperly sanitized before being passed to operating system command execution functions. This allows specially crafted input containing command metacharacters or shell commands to be interpreted and executed by the underlying operating system shell. The lack of proper input filtering, encoding, or parameterization enables command injection attacks.

Attack Vector

The attack vector is network-based, targeting the web-based management interface of Cisco HyperFlex HX devices. An attacker can craft malicious HTTP requests containing command injection payloads in vulnerable parameters. When the management interface processes these requests, the injected commands are executed with root privileges on the underlying operating system. No authentication is required, and the attack can be performed remotely without any user interaction.

The exploitation mechanism involves sending specially crafted requests to vulnerable endpoints in the HyperFlex management interface. The attacker injects shell metacharacters and commands that bypass insufficient input validation, resulting in arbitrary command execution. For detailed technical information, refer to the Packet Storm Exploit Report and the Cisco Security Advisory.

Detection Methods for CVE-2021-1498

Indicators of Compromise

• Suspicious HTTP requests to the HyperFlex web management interface containing shell metacharacters (;, |, $(), backticks)
• Unexpected process execution originating from web server processes on HyperFlex nodes
• Anomalous outbound network connections from HyperFlex management interfaces
• Creation of unexpected user accounts or modification of system configuration files

Detection Strategies

• Monitor web server logs for requests containing command injection patterns such as pipe characters, semicolons, or command substitution syntax
• Implement network intrusion detection rules to identify exploitation attempts targeting HyperFlex management interfaces
• Deploy endpoint detection solutions to monitor for anomalous process creation chains originating from web application processes
• Review authentication logs for signs of unauthorized access following successful exploitation

Monitoring Recommendations

• Enable verbose logging on Cisco HyperFlex management interfaces and centralize logs for analysis
• Implement network segmentation to isolate HyperFlex management interfaces from untrusted networks
• Deploy a web application firewall (WAF) with rules to detect and block command injection attempts
• Establish baseline behavior for HyperFlex nodes and alert on deviations indicating potential compromise

How to Mitigate CVE-2021-1498

Immediate Actions Required

• Apply the security patches provided by Cisco immediately to all affected HyperFlex HX devices
• Restrict network access to HyperFlex management interfaces, allowing only trusted administrator IP addresses
• Review system logs for evidence of exploitation attempts or successful compromise
• If compromise is suspected, isolate affected systems and conduct forensic investigation before remediation

Patch Information

Cisco has released security updates to address this vulnerability. Administrators should consult the Cisco Security Advisory for specific patch versions and upgrade instructions. Given that this vulnerability is actively exploited in the wild and listed in CISA's KEV catalog, patching should be treated as an urgent priority.

Workarounds

• Implement strict network access controls to limit connectivity to HyperFlex management interfaces from trusted networks only
• Deploy a reverse proxy or web application firewall in front of management interfaces to filter malicious requests
• Disable remote management access if not operationally required until patches can be applied
• Monitor for indicators of compromise while awaiting patch deployment

# Example: Restrict management interface access using firewall rules
# Allow only trusted management network
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Verify HyperFlex software version after patching
# Consult Cisco documentation for version verification commands