The vulnerability identified as CVE-2026-41429 is classified as high severity with a CVSS score of 8.8. It affects the arduino-esp32 core for various ESP32 microcontrollers, including ESP32, ESP32-S2, ESP32-S3, ESP32-C3, ESP32-C6, and ESP32-H2.
This vulnerability allows for remote memory corruption through the NBNS packet handling path. When the NetBIOS service is activated via NBNS.begin(...), the device listens on UDP port 137 and processes untrusted NBNS requests. The vulnerability arises from the request parser trusting the attacker-controlled name_len field without enforcing proper bounds, leading to potential exploitation.
It is imperative for organizations using affected versions to prioritize patching to version 3.3.8, which mitigates this issue. The risk to organizations includes unauthorized access and potential data loss, emphasizing the need for immediate action.
The vulnerability was published on April 24, 2026, and remains under active scrutiny for potential exploitation. As of now, no public exploits have been confirmed.
Organizations should monitor network traffic for unusual NBNS requests, especially from untrusted sources, to detect potential attempts to exploit this vulnerability.
Vulnerability Details
The official description indicates that the vulnerability exists in the NBNS handling path of the arduino-esp32 core. This issue is categorized under CWE-121, indicating improper validation of input size, which can lead to memory corruption.
The CVSS 3.1 vector for this vulnerability is CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, denoting an adjacent network attack vector, low attack complexity, and no privileges or user interaction required for exploitation.
The confidentiality, integrity, and availability impacts are all rated as high, demonstrating the potentially severe consequences of successful exploitation.
Technical Analysis
The root cause of this vulnerability lies in the handling of the name_len field in NBNS requests. The parser does not properly validate the length of this field, which is exploited by attackers to overwrite memory buffers. This flaw allows attackers to send maliciously crafted NBNS requests that can lead to arbitrary code execution or crashing the device.
The attack vector is classified as adjacent network, meaning that an attacker must be on the same local network to exploit this vulnerability. The attack complexity is low, indicating that no specialized skills are necessary for exploitation. Additionally, no privileges are required, and user interaction is not necessary.
Given the high impacts on confidentiality, integrity, and availability, organizations must treat this vulnerability with urgency. Monitoring for unusual network activity related to NBNS requests can help in early detection of potential exploitation efforts.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2026-41429 is significant, especially for organizations utilizing the affected Arduino ESP32 components in their infrastructure. An attacker on the same network can exploit this vulnerability to execute arbitrary code, potentially leading to unauthorized access to sensitive data and systems.
This situation poses a notable blast radius, as the vulnerability can be leveraged against multiple devices within the same network. Therefore, the urgency for organizations to address this vulnerability is high, especially in light of the potential for widespread impact across interconnected devices.
Given the CVSS score of 8.8 and the associated exploitability, organizations should prioritize patching this vulnerability immediately. The risk to organizations includes not only financial loss but also reputational damage stemming from data breaches or service disruptions.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
This vulnerability affects all versions of the arduino-esp32 core prior to 3.3.8. Organizations should ensure they are using the latest version to mitigate this risk.
Mitigation & Remediation
To remediate this vulnerability, organizations must upgrade their arduino-esp32 core to version 3.3.8 or later. If immediate patching is not feasible, consider implementing network controls to restrict access to UDP port 137 and monitor for unusual NBNS traffic.
For further guidance, organizations can refer to our application security assessment services to help identify and mitigate vulnerabilities in their systems.
Detection Guidance
Organizations should monitor their logs for indicators of NBNS request anomalies, including unusually large name_len values or requests from unexpected sources. Behavioral anomalies in device responses can also indicate potential exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2026-41429 lies in its demonstration of the risks associated with improper input validation in network protocols. This vulnerability highlights the importance of robust security practices in firmware development and the need for organizations to maintain a proactive security posture.
Security teams should take note of this vulnerability as a critical lesson in the importance of validating all network inputs. Regular vulnerability assessments and penetration testing, such as our red teaming services, can help identify similar weaknesses before they can be exploited.
The patterns exhibited by this vulnerability can serve as a precursor for future vulnerabilities in similar products. Organizations must stay vigilant and continuously adapt their security strategies to address evolving threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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