Prior to version 3.3.8 the Arduino core for ESP32 devices parses NetBIOS Name Service (NBNS) packets without validating the name_len field and copies the resulting payload into a fixed‑size buffer. This flaw allows an attacker on the same local network to send a crafted UDP packet to port 137 and trigger a memory corruption that can lead to arbitrary code execution or system crash. The vulnerability is listed under CWE‑121, a stack buffer overflow. The high CVSS score of 8.8 reflects the potential for severe impact on confidentiality, integrity, and availability when the flaw is exploited.

The affected product is espressif:arduino-esp32, the Arduino core for ESP32, ESP32‑S2, ESP32‑S3, ESP32‑C3, ESP32‑C6 and ESP32‑H2 microcontrollers. All releases prior to 3.3.8 are vulnerable; the flaw is fixed in version 3.3.8 and later.

CVSS 8.8 places this issue in the high severity range, and the EPSS score of less than 1% indicates a low but non‑zero likelihood of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog, yet it can be exploited by an adversary who can send packets to the affected device from the local network. The actor needs only local network access; network segmentation or firewall rules that block UDP port 137 reduce the attack surface. Because the flaw leads to memory corruption, an exploit could achieve arbitrary code execution or denial of service depending on the device configuration.