CVE-2026-7426: FreeRTOS-Plus-TCP IPv6 RA Heap Overflow
The National Vulnerability Database has detailed CVE-2026-7426, a critical heap buffer overflow vulnerability in FreeRTOS-Plus-TCP versions before V4.2.6 and V4.4.1. This flaw stems from insufficient validation of the prefix length field within IPv6 Router Advertisement (RA) processing. An adjacent network actor can exploit this by crafting and sending an RA with an excessive prefix length, leading directly to memory corruption.
This vulnerability carries a CVSS score of 8.1 (HIGH), signaling a significant risk. Crucially, only systems processing IPv6 Router Advertisements are affected; those limited to IPv4 RA are not impacted. The attacker’s calculus here is straightforward: proximity to the target and a malformed packet are all that’s required to potentially destabilize or compromise an embedded device, making it a low-friction, high-impact attack vector for specific environments.
Defenders need to grasp the implications for their IoT and embedded device ecosystems. FreeRTOS is pervasive. While the specific affected products are not detailed in the National Vulnerability Database’s advisory, the widespread use of FreeRTOS-Plus-TCP means this could impact a vast array of devices. The recommended mitigation is to upgrade to the fixed version as soon as it becomes available. This is not a ‘wait and see’ situation; if you’re running vulnerable versions and processing IPv6 RAs, you’re exposed.
What This Means For You
- If your organization deploys devices utilizing FreeRTOS-Plus-TCP and processes IPv6 Router Advertisements, you are directly exposed to CVE-2026-7426. Prioritize identifying all such devices within your network and prepare for immediate patching to the fixed version once released. This vulnerability allows for memory corruption from an adjacent network actor, which means critical infrastructure or sensitive IoT devices could be targeted.
Related ATT&CK Techniques
🛡️ Detection Rules
1 rule · 6 SIEM formats1 detection rule auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
Exploitation Attempt — CVE-2026-7426
title: Exploitation Attempt — CVE-2026-7426
id: scw-2026-04-29-evt-1
status: experimental
level: high
description: |
Monitor for exploitation attempts targeting CVE-2026-7426. Patch immediately if running affected CVE-2026-7426 products.
author: SCW Feed Engine (auto-generated)
date: 2026-04-29
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-7426/
tags:
- attack.general
- attack.vulnerability
logsource:
category: webserver
detection:
selection:
cs-uri-query|contains:
- 'CVE-2026-7426'
sc-status:
- 200
- 500
condition: selection
falsepositives:
- Legitimate activity from CVE-2026-7426
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-7426 | Memory Corruption | FreeRTOS-Plus-TCP before V4.2.6 |
| CVE-2026-7426 | Memory Corruption | FreeRTOS-Plus-TCP before V4.4.1 |
| CVE-2026-7426 | Buffer Overflow | Heap buffer overflow in IPv6 Router Advertisement processing due to insufficient validation of prefix length field |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | April 29, 2026 at 23:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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