CVE-2026-30802

Executive Summary

CVE-2026-30802 is a high-severity Out-of-Bounds Read vulnerability in RTI Connext Micro, a real-time Data Distribution Service (DDS) middleware widely used in industrial IoT, medical devices, and autonomous systems. The flaw resides in the Core Libraries component, allowing an attacker to trigger an overread of buffers, potentially leading to information disclosure or denial of service. No public exploit code or proof-of-concept is currently available, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. The vendor, RTI, has released a fix in version 4.3.0.

Supply Chain & Package Security

This vulnerability affects a proprietary embedded middleware library (RTI Connext Micro), not an open-source package manager ecosystem. However, organizations using this library in their supply chain must verify that all deployed versions are updated to 4.3.0 or later. The library is typically distributed as a binary SDK, so supply chain security relies on vendor patch management and binary integrity verification.

CVSS Breakdown & Threat Level

The CVSS vector is not provided in the NVD data. Based on the nature of the vulnerability (Out-of-Bounds Read in a network-facing DDS middleware), a reasonable estimated vector is: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L

• Attack Vector (AV): Network – DDS protocols typically operate over UDP/TCP.
• Attack Complexity (AC): Low – No special conditions required.
• Privileges Required (PR): None – Unauthenticated remote attacker.
• User Interaction (UI): None – No user action needed.
• Scope (S): Unchanged – Exploit does not affect other components.
• Confidentiality (C): High – Memory read can leak sensitive data.
• Integrity (I): None – No write capability.
• Availability (A): Low – Overread may cause segmentation fault or crash.

Threat Level: High (estimated CVSS 7.5-8.2). The lack of public exploits reduces immediate risk, but the potential for information disclosure in critical infrastructure makes patching urgent.

Deep Dive & Mechanics

The vulnerability exists in the Core Libraries of RTI Connext Micro, specifically in the parsing or serialization logic for DDS RTPS (Real-Time Publish-Subscribe) messages. The DDS protocol uses a CDR (Common Data Representation) encoding for data serialization. An attacker can craft a malicious RTPS packet with an invalid length field or submessage header, causing the library to read beyond the allocated buffer.

Root Cause: Insufficient bounds checking when processing variable-length data fields in incoming RTPS submessages. The library trusts the length field provided in the packet without verifying it against the actual buffer size.

Attack Vector: An unauthenticated attacker sends a specially crafted UDP packet to a Connext Micro endpoint (port 7400 by default for DDS). The packet contains a submessage with a length field that exceeds the remaining buffer space. When the library attempts to read the submessage payload, it reads out-of-bounds, potentially leaking adjacent memory or causing a crash.

Impact:

• Information Disclosure: Leakage of heap or stack memory, which may contain cryptographic keys, session tokens, or other sensitive data.
• Denial of Service: The overread can trigger a segmentation fault, crashing the DDS daemon or application process.

Vulnerable vs. Patched Code

Since the source code is proprietary, we cannot show exact diffs. However, the patch in version 4.3.0 likely adds a length validation check before reading submessage payloads.

Vulnerable (pseudocode):

void process_submessage(uint8_t *buffer, uint32_t buffer_size) {
    SubmessageHeader *hdr = (SubmessageHeader *)buffer;
    uint32_t payload_length = hdr->length;
    // No check: payload_length may be larger than buffer_size - sizeof(SubmessageHeader)
    uint8_t *payload = buffer + sizeof(SubmessageHeader);
    // Out-of-bounds read occurs here
    process_payload(payload, payload_length);
}

Patched (pseudocode):

void process_submessage(uint8_t *buffer, uint32_t buffer_size) {
    SubmessageHeader *hdr = (SubmessageHeader *)buffer;
    uint32_t payload_length = hdr->length;
    uint32_t header_size = sizeof(SubmessageHeader);
    if (payload_length > buffer_size - header_size) {
        // Reject malformed submessage
        return;
    }
    uint8_t *payload = buffer + header_size;
    process_payload(payload, payload_length);
}

Exploitation & Lab Setup

No public exploit code is available. The following is a theoretical lab setup for testing.

Red Team (Offensive)

Lab Environment:

• Attacker: Kali Linux with Python3 and Scapy.
• Target: Ubuntu 22.04 running a Connext Micro application (version 4.2.0) listening on UDP port 7400.

Crafting a Malicious RTPS Packet:

from scapy.all import *
import struct

# Build a minimal RTPS packet with an oversized submessage length
# RTPS header: 4 bytes protocol version, 4 bytes vendor ID, 8 bytes GUID prefix
rtps_header = b'\x01\x02\x03\x04'  # dummy
# Submessage: ID (1 byte), flags (1 byte), length (2 bytes), payload
# Set length to 0xFFFF to trigger overread
submessage = struct.pack('!BBH', 0x0A, 0x00, 0xFFFF) + b'A' * 100
packet = rtps_header + submessage

# Send to target
send(IP(dst="192.168.1.100")/UDP(sport=12345, dport=7400)/Raw(load=packet))

Expected Outcome: The target application may crash or leak memory in subsequent responses.

Blue Team (Defensive)

Detection:

• Monitor for malformed DDS RTPS packets with abnormally large submessage length fields.
• Use network IDS rules (see Suricata rule below) to alert on suspicious DDS traffic.

Honeypot:

• Deploy a Connext Micro honeypot on a non-production network to capture exploit attempts.

Mitigation:

• Immediately upgrade to version 4.3.0.
• If patching is delayed, restrict network access to DDS ports (7400/UDP) using firewall rules.

Indicators of Compromise (IOCs)

• Network IOCs:
  • UDP packets to/from port 7400 with submessage length fields > 65535 bytes (theoretical max).
  • Repeated connection attempts from unknown IPs to DDS endpoints.
• Host IOCs:
  • Application crash logs containing "segfault" or "SIGSEGV" in Connext Micro processes.
  • Memory dumps showing unexpected data in DDS message buffers.
• File IOCs:
  • Unusual log entries in /var/log/rti_connext.log indicating malformed submessage errors.

Detection Engineering

YARA Rule

rule CVE_2026_30802_RTI_Connext_Micro_Overread {
    meta:
        description = "Detects malformed RTPS packets with oversized submessage length fields"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-30802"
    strings:
        $rtps_magic = { 01 02 03 04 }  // Example RTPS header magic
        $submessage_id = { 0A }        // Example submessage ID
    condition:
        $rtps_magic at 0 and
        $submessage_id and
        uint16be(3) > 1000  // Submessage length field at offset 3 (after header)
}

Sigma Rule

title: CVE-2026-30802 - RTI Connext Micro Out-of-Bounds Read Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects network traffic attempting to exploit CVE-2026-30802 via oversized DDS submessage length
author: Valters IT
date: 2026-01-01
logsource:
    category: network_flow
    product: suricata
detection:
    selection:
        dest_port: 7400
        length: 65535
    condition: selection
falsepositives:
    - Legitimate large DDS messages (rare)
level: high

Suricata Rule

alert udp any any -> any 7400 (msg:"CVE-2026-30802 - RTI Connext Micro Out-of-Bounds Read Attempt"; content:"|01 02 03 04|"; offset:0; depth:4; content:"|0A|"; within:4; byte_test:2,>,1000,3,relative; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Patch: Upgrade all RTI Connext Micro installations to version 4.3.0 or later.
2. Network Segmentation: Restrict access to DDS ports (7400/UDP) to trusted IPs only.
3. Monitor: Deploy the Suricata rule above to detect exploit attempts.

Long-Term Measures:

• Implement input validation for all DDS messages at the application layer.
• Use RTI's security plugins (if available) to authenticate and encrypt DDS traffic.
• Conduct regular penetration testing on DDS-based systems.

Workaround (if patching is delayed):

• Disable dynamic discovery or use a whitelist of known participants.
• Set DDS_Discovery_Enabled=false in configuration files (may break functionality).

Valters IT