What’s Vulnerable › Vulnerabilities

CVE-2026-41429: Improper validation of NBNS name_len in arduino-esp32 NetBIOS leads to memory corruption

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-24 · updated 2026-10-26
• Weakness: CWE-121

Description

arduino-esp32 is an Arduino core for the ESP32, ESP32-S2, ESP32-S3, ESP32-C3, ESP32-C6 and ESP32-H2 microcontrollers. Prior to 3.3.8, there is a remotely reachable memory corruption issue in the NBNS packet handling path. When NetBIOS is enabled by calling NBNS.begin(...), the device listens on UDP port 137 and processes untrusted NBNS requests from the local network. The request parser trusts the attacker-controlled name_len field without enforcing a bound consistent with the fixed-size destination buffers used later in the flow. This vulnerability is fixed in 3.3.8.

Affected products

• espressif arduino-esp32: before 3.3.8 — fixed in 3.3.8

How to fix

Upgrade to a fixed version: espressif arduino-esp32 3.3.8. Check the vendor advisory for mitigations.

References

• https://github.com/espressif/arduino-esp32/security/advisories/GHSA-92j9-c75g-2c5f
• https://github.com/espressif/arduino-esp32/security/advisories/GHSA-92j9-c75g-2c5f

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