CVE-2026-0619

Executive Summary

CVE-2026-0619 is a denial-of-service (DoS) vulnerability in Silicon Labs' Matter SDK, caused by a reachable infinite loop triggered via an integer wraparound. An attacker can exploit this flaw to crash a device running the affected SDK, requiring a hard reset to recover. No public exploit code or patch details are currently available. The vulnerability has a CVSS score of 0.0 (likely unassigned or placeholder), but the underlying integer overflow (CWE-190) can lead to severe service disruption in IoT environments.

Supply Chain & Package Security

This vulnerability affects the Silicon Labs Matter SDK, which is a critical component in the Matter smart home ecosystem. Organizations using this SDK in their products should monitor for updates from Silicon Labs and consider supply chain risk assessments for affected firmware.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unassigned / Placeholder)
• Attack Vector: Network (likely)
• Attack Complexity: Low (integer wraparound is often exploitable without special conditions)
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: None
• Availability Impact: High (device crash requiring hard reset)
• Threat Level: Medium (due to DoS impact and lack of patch)

Deep Dive & Mechanics

The vulnerability resides in the Matter SDK's handling of integer values during message processing. An integer wraparound occurs when a calculation exceeds the maximum value of an integer type, causing it to wrap to a negative or very small value. This can lead to an infinite loop in a loop construct that depends on the integer value, consuming all CPU resources and causing a denial of service.

Root Cause:
The SDK fails to validate integer bounds before using them in loop conditions. An attacker can send a crafted message that triggers an integer overflow, causing a loop to run indefinitely.

Attack Vector:
An unauthenticated attacker on the same network can send a specially crafted Matter protocol message to the target device.

Impact:
The device becomes unresponsive and requires a physical hard reset (power cycle) to recover. No data is compromised, but availability is severely impacted.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described conceptually:

Vulnerable Code (Conceptual):

int process_message(uint8_t *data, uint16_t length) {
    uint16_t count = (data[0] << 8) | data[1]; // Attacker-controlled
    for (uint16_t i = 0; i < count; i++) {
        // Process data
    }
    return 0;
}

If count is set to a value that, when used in the loop, causes an integer wraparound (e.g., count = 0 or count = 65535 with certain operations), the loop may become infinite.

Patched Code (Conceptual):

int process_message(uint8_t *data, uint16_t length) {
    uint16_t count = (data[0] << 8) | data[1];
    if (count > MAX_PROCESSING_LIMIT) {
        return -1; // Reject oversized count
    }
    for (uint16_t i = 0; i < count; i++) {
        // Process data
    }
    return 0;
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• A device running Silicon Labs Matter SDK (any version)
• Network access to the device (same subnet)
• Ability to send raw Matter protocol messages

Exploitation Steps:

1. Identify the target device's IP address and Matter port (typically 5540).
2. Craft a Matter message with a manipulated integer field that triggers an integer wraparound.
3. Send the message to the device.
4. Observe the device becoming unresponsive (DoS).
5. The device requires a hard reset to recover.

Example Payload (Conceptual):

import socket

target_ip = "192.168.1.100"
target_port = 5540

# Craft a message that triggers integer wraparound
# This is a simplified example; actual Matter protocol requires proper framing
payload = b"\x00\x00"  # Placeholder for integer field
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.sendto(payload, (target_ip, target_port))
sock.close()

Blue Team

Detection:

• Monitor for anomalous network traffic to Matter ports (5540/UDP).
• Look for repeated connection attempts or malformed packets.
• Use network intrusion detection systems (NIDS) to flag potential integer overflow attempts.

Mitigation:

• Isolate Matter devices on a separate VLAN.
• Implement rate limiting on Matter protocol messages.
• Monitor device health and automatically reboot if unresponsive.

Indicators of Compromise (IOCs)

• Network: UDP packets to port 5540 with malformed or oversized integer fields.
• System: Device becomes unresponsive, requiring hard reset.
• Logs: No logs generated (DoS prevents logging).

Detection Engineering

YARA Rule

rule CVE_2026_0619_Matter_DoS {
    meta:
        description = "Detects potential integer wraparound exploit in Matter SDK"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-0619"
    strings:
        $matter_header = { 00 00 00 00 }  // Placeholder for Matter protocol header
        $integer_field = { FF FF }        // Example of large integer value
    condition:
        $matter_header at 0 and $integer_field
}

Sigma Rule

title: CVE-2026-0619 Matter SDK DoS Exploit Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects network traffic targeting Matter devices with potential integer overflow
author: Valters IT
date: 2025/04/10
logsource:
    category: network_connection
    product: suricata
detection:
    selection:
        dest_port: 5540
        protocol: udp
        payload|contains: "FF FF"  # Example pattern
    condition: selection
falsepositives:
    - Legitimate Matter traffic with large payloads
level: medium

Suricata Rule

alert udp any any -> any 5540 (msg:"CVE-2026-0619 Matter SDK DoS Attempt"; content:"|FF FF|"; depth:100; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices on a separate network segment.
2. Implement network-level filtering to block malformed Matter packets.
3. Monitor device health and implement automatic recovery (e.g., watchdog timer).

Long-Term Fix:

• Apply a patch from Silicon Labs when available.
• Update the Matter SDK to a version that includes integer overflow validation.
• Conduct code review for similar integer handling issues.

Workaround:

• Disable Matter protocol if not required.
• Use a firewall to restrict access to Matter ports.

Valters IT signature: This report is provided for educational and defensive purposes only. Unauthorized exploitation of this vulnerability is illegal.