CVE-2026-22844

Executive Summary

CVE-2026-22844 is a critical Command Injection vulnerability in Zoom Node Multimedia Routers (MMRs) prior to version 5.2.1716.0. The flaw allows an unauthenticated meeting participant to execute arbitrary commands on the MMR via network access, leading to full remote code execution. With a CVSS score of 9.9, this vulnerability poses an extreme risk to Zoom infrastructure and any organization using affected MMRs for video conferencing. No public exploit code or proof-of-concept is currently available, but the attack vector is network-based and requires no authentication, making it highly exploitable once details emerge.

CVSS Breakdown & Threat Level

• CVSS Score: 9.9 (Critical)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

The threat level is critical due to the lack of authentication required, low complexity, and full impact on confidentiality, integrity, and availability. An attacker can completely compromise the MMR, potentially pivoting to internal networks or disrupting Zoom services.

Deep Dive & Mechanics

The vulnerability resides in the command parsing logic of Zoom MMRs. The MMR processes meeting-related commands from participants over the network. Due to insufficient input sanitization, an attacker can inject arbitrary operating system commands into a parameter that is passed to a shell execution function. For example, a crafted network packet containing a command separator (e.g., ;, |, &&) followed by malicious commands can be executed with the privileges of the MMR process.

The MMR likely uses a function similar to system() or exec() in C/C++ to handle certain administrative or diagnostic commands. The injection point is in the handling of meeting control messages, where user-supplied data is concatenated into a command string without proper escaping or validation.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

void handle_meeting_command(char *user_input) {
    char cmd[512];
    snprintf(cmd, sizeof(cmd), "process_meeting %s", user_input);
    system(cmd);  // Vulnerable to command injection
}

Patched Code (Conceptual):

void handle_meeting_command(char *user_input) {
    // Sanitize input: allow only alphanumeric and specific safe characters
    if (!is_safe_input(user_input)) {
        log_error("Invalid input");
        return;
    }
    // Use execve with fixed arguments instead of system()
    char *args[] = {"process_meeting", user_input, NULL};
    execve("/usr/bin/process_meeting", args, NULL);
}

The patch likely involves input validation, escaping shell metacharacters, and replacing system() with safer execution methods like execve().

Exploitation & Lab Setup

Red Team

Exploitation Steps:

1. Identify a vulnerable Zoom MMR (version < 5.2.1716.0) on the network.
2. Send a crafted network packet to the MMR's meeting control port (e.g., TCP 443 or a custom port) with a command injection payload.
3. Example payload: ;id or | whoami appended to a legitimate meeting parameter.
4. The MMR executes the injected command, returning output or allowing further exploitation.

Proof-of-Concept (Conceptual):

import socket

target_ip = "192.168.1.100"
port = 443
payload = b"MEETING_CMD;id"

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((target_ip, port))
sock.send(payload)
response = sock.recv(4096)
print(response.decode())
sock.close()

Blue Team

Detection & Response:

• Monitor network traffic for unusual command sequences in meeting control packets.
• Deploy network intrusion detection systems (NIDS) with signatures for command injection patterns.
• Isolate MMRs from untrusted networks and restrict access to only necessary ports.
• Implement strict input validation on all MMR endpoints.

Indicators of Compromise (IOCs)

• Network Traffic: Unusual command separators (;, |, &&) in meeting control packets.
• Logs: Unexpected shell commands executed by the MMR process (e.g., id, whoami, cat /etc/passwd).
• File System: Presence of unauthorized files or scripts in /tmp or MMR directories.
• Processes: Unusual child processes spawned by the MMR binary (e.g., /bin/sh, /bin/bash).

Detection Engineering

YARA Rule

rule CVE_2026_22844_Command_Injection {
    meta:
        description = "Detects command injection attempts targeting Zoom MMR"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2026-22844"
    strings:
        $cmd1 = /[;&|`]\s*(id|whoami|cat|ls|echo|nc|bash|sh|python|perl|wget|curl)/
        $cmd2 = /system\(|exec\(|popen\(/
    condition:
        any of ($cmd1) or $cmd2
}

Sigma Rule

title: CVE-2026-22844 Command Injection on Zoom MMR
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects command injection attempts in network traffic to Zoom MMR
author: Valters IT
logsource:
    category: network_connection
    product: suricata
detection:
    selection:
        dest_port: 443
        payload|contains:
            - ';id'
            - '|whoami'
            - '&&cat'
            - '`ls'
    condition: selection
falsepositives:
    - Legitimate use of special characters in meeting names (unlikely)
level: critical

Suricata Rule

alert tcp any any -> any 443 (msg:"CVE-2026-22844 Zoom MMR Command Injection"; flow:to_server,established; content:";id"; nocase; content:"|whoami"; distance:0; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Isolate all Zoom MMRs from untrusted networks. Restrict access to only necessary IP addresses.
2. Short-term: Apply vendor patch once available. Monitor Zoom's security advisories for updates.
3. Long-term: Implement network segmentation for MMRs. Use web application firewalls (WAF) to filter malicious payloads. Enforce strict input validation on all MMR endpoints.
4. Compensating Controls: Deploy host-based intrusion detection (HIDS) on MMRs. Enable logging and alerting for unusual process execution.

Valters IT